Remove dependency on error ordering in isolation tests

We now report errors reported by the just-unblocked and unblocking
transactions identically; this should fix relatively common buildfarm
failures reported by animals that are failing the "wrong" session.

8 files changed, 107 insertions, 142 deletions

diff --git a/src/test/isolation/expected/fk-deadlock.out b/src/test/isolation/expected/fk-deadlock.out
index 2f4f71122e8..36813f11f51 100644
--- a/src/test/isolation/expected/fk-deadlock.out
+++ b/src/test/isolation/expected/fk-deadlock.out
@@ -23,7 +23,7 @@ step s2i: INSERT INTO child VALUES (2, 1);
 step s1u: UPDATE parent SET aux = 'bar'; <waiting ...>
 step s2u: UPDATE parent SET aux = 'baz';
 step s1u: <... completed>
-ERROR:  deadlock detected
+error in steps s2u s1u: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -32,8 +32,8 @@ step s1i: INSERT INTO child VALUES (1, 1);
 step s2i: INSERT INTO child VALUES (2, 1);
 step s2u: UPDATE parent SET aux = 'baz'; <waiting ...>
 step s1u: UPDATE parent SET aux = 'bar';
-ERROR:  deadlock detected
 step s2u: <... completed>
+error in steps s1u s2u: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -43,7 +43,7 @@ step s1i: INSERT INTO child VALUES (1, 1);
 step s1u: UPDATE parent SET aux = 'bar'; <waiting ...>
 step s2u: UPDATE parent SET aux = 'baz';
 step s1u: <... completed>
-ERROR:  deadlock detected
+error in steps s2u s1u: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -52,8 +52,8 @@ step s2i: INSERT INTO child VALUES (2, 1);
 step s1i: INSERT INTO child VALUES (1, 1);
 step s2u: UPDATE parent SET aux = 'baz'; <waiting ...>
 step s1u: UPDATE parent SET aux = 'bar';
-ERROR:  deadlock detected
 step s2u: <... completed>
+error in steps s1u s2u: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
diff --git a/src/test/isolation/expected/fk-deadlock2.out b/src/test/isolation/expected/fk-deadlock2.out
index 18015408161..2d8e5e5b25f 100644
--- a/src/test/isolation/expected/fk-deadlock2.out
+++ b/src/test/isolation/expected/fk-deadlock2.out
@@ -23,7 +23,7 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -33,7 +33,7 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -42,8 +42,8 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -52,8 +52,8 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -63,7 +63,7 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -73,7 +73,7 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -82,8 +82,8 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -92,8 +92,8 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
diff --git a/src/test/isolation/expected/fk-deadlock2_1.out b/src/test/isolation/expected/fk-deadlock2_1.out
index 8ccc24a2abf..30c4c998631 100644
--- a/src/test/isolation/expected/fk-deadlock2_1.out
+++ b/src/test/isolation/expected/fk-deadlock2_1.out
@@ -14,7 +14,7 @@ step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1c: COMMIT;
 step s2u1: <... completed>
-ERROR:  could not serialize access due to concurrent update
+error in steps s1c s2u1: ERROR:  could not serialize access due to concurrent update
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 ERROR:  current transaction is aborted, commands ignored until end of transaction block
 step s2c: COMMIT;
@@ -25,7 +25,7 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -35,7 +35,7 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -44,8 +44,8 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -54,8 +54,8 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -65,7 +65,7 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -75,7 +75,7 @@ step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u2: <... completed>
-ERROR:  deadlock detected
+error in steps s2u2 s1u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -84,8 +84,8 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -94,8 +94,8 @@ step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
 step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
 step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
 step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
 step s2u2: <... completed>
+error in steps s1u2 s2u2: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
diff --git a/src/test/isolation/expected/fk-deadlock2_2.out b/src/test/isolation/expected/fk-deadlock2_2.out
deleted file mode 100644
index d61b1ed4712..00000000000
--- a/src/test/isolation/expected/fk-deadlock2_2.out
+++ /dev/null
@@ -1,110 +0,0 @@
-Parsed test spec with 2 sessions
-
-starting permutation: s1u1 s1u2 s1c s2u1 s2u2 s2c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1c: COMMIT;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2c: COMMIT;
-
-starting permutation: s1u1 s1u2 s2u1 s1c s2u2 s2c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s1c: COMMIT;
-step s2u1: <... completed>
-ERROR:  could not serialize access due to concurrent update
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  current transaction is aborted, commands ignored until end of transaction block
-step s2c: COMMIT;
-
-starting permutation: s1u1 s2u1 s1u2 s2u2 s1c s2c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: <... completed>
-ERROR:  deadlock detected
-step s1c: COMMIT;
-step s2c: COMMIT;
-
-starting permutation: s1u1 s2u1 s1u2 s2u2 s2c s1c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: <... completed>
-ERROR:  deadlock detected
-step s2c: COMMIT;
-step s1c: COMMIT;
-
-starting permutation: s1u1 s2u1 s2u2 s1u2 s1c s2c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
-step s2u2: <... completed>
-step s1c: COMMIT;
-step s2c: COMMIT;
-
-starting permutation: s1u1 s2u1 s2u2 s1u2 s2c s1c
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
-step s2u2: <... completed>
-step s2c: COMMIT;
-step s1c: COMMIT;
-
-starting permutation: s2u1 s1u1 s1u2 s2u2 s1c s2c
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: <... completed>
-ERROR:  deadlock detected
-step s1c: COMMIT;
-step s2c: COMMIT;
-
-starting permutation: s2u1 s1u1 s1u2 s2u2 s2c s1c
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u2: <... completed>
-ERROR:  deadlock detected
-step s2c: COMMIT;
-step s1c: COMMIT;
-
-starting permutation: s2u1 s1u1 s2u2 s1u2 s1c s2c
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
-step s2u2: <... completed>
-step s1c: COMMIT;
-step s2c: COMMIT;
-
-starting permutation: s2u1 s1u1 s2u2 s1u2 s2c s1c
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  deadlock detected
-step s2u2: <... completed>
-step s2c: COMMIT;
-step s1c: COMMIT;
-
-starting permutation: s2u1 s2u2 s1u1 s2c s1u2 s1c
-step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-step s1u1: UPDATE A SET Col1 = 1 WHERE AID = 1; <waiting ...>
-step s2c: COMMIT;
-step s1u1: <... completed>
-step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
-ERROR:  could not serialize access due to concurrent update
-step s1c: COMMIT;
diff --git a/src/test/isolation/expected/fk-deadlock_1.out b/src/test/isolation/expected/fk-deadlock_1.out
index 69540b09346..ca75322cc12 100644
--- a/src/test/isolation/expected/fk-deadlock_1.out
+++ b/src/test/isolation/expected/fk-deadlock_1.out
@@ -14,7 +14,7 @@ step s1u: UPDATE parent SET aux = 'bar';
 step s2i: INSERT INTO child VALUES (2, 1); <waiting ...>
 step s1c: COMMIT;
 step s2i: <... completed>
-ERROR:  could not serialize access due to concurrent update
+error in steps s1c s2i: ERROR:  could not serialize access due to concurrent update
 step s2u: UPDATE parent SET aux = 'baz';
 ERROR:  current transaction is aborted, commands ignored until end of transaction block
 step s2c: COMMIT;
@@ -25,7 +25,7 @@ step s2i: INSERT INTO child VALUES (2, 1);
 step s1u: UPDATE parent SET aux = 'bar'; <waiting ...>
 step s2u: UPDATE parent SET aux = 'baz';
 step s1u: <... completed>
-ERROR:  deadlock detected
+error in steps s2u s1u: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -34,8 +34,8 @@ step s1i: INSERT INTO child VALUES (1, 1);
 step s2i: INSERT INTO child VALUES (2, 1);
 step s2u: UPDATE parent SET aux = 'baz'; <waiting ...>
 step s1u: UPDATE parent SET aux = 'bar';
-ERROR:  deadlock detected
 step s2u: <... completed>
+error in steps s1u s2u: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -45,7 +45,7 @@ step s1i: INSERT INTO child VALUES (1, 1);
 step s1u: UPDATE parent SET aux = 'bar'; <waiting ...>
 step s2u: UPDATE parent SET aux = 'baz';
 step s1u: <... completed>
-ERROR:  deadlock detected
+error in steps s2u s1u: ERROR:  deadlock detected
 step s1c: COMMIT;
 step s2c: COMMIT;
 
@@ -54,8 +54,8 @@ step s2i: INSERT INTO child VALUES (2, 1);
 step s1i: INSERT INTO child VALUES (1, 1);
 step s2u: UPDATE parent SET aux = 'baz'; <waiting ...>
 step s1u: UPDATE parent SET aux = 'bar';
-ERROR:  deadlock detected
 step s2u: <... completed>
+error in steps s1u s2u: ERROR:  deadlock detected
 step s2c: COMMIT;
 step s1c: COMMIT;
 
@@ -65,7 +65,7 @@ step s2u: UPDATE parent SET aux = 'baz';
 step s1i: INSERT INTO child VALUES (1, 1); <waiting ...>
 step s2c: COMMIT;
 step s1i: <... completed>
-ERROR:  could not serialize access due to concurrent update
+error in steps s2c s1i: ERROR:  could not serialize access due to concurrent update
 step s1u: UPDATE parent SET aux = 'bar';
 ERROR:  current transaction is aborted, commands ignored until end of transaction block
 step s1c: COMMIT;
diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c
index 01640124d0c..023e4dc222b 100644
--- a/src/test/isolation/isolationtester.c
+++ b/src/test/isolation/isolationtester.c
@@ -384,6 +384,50 @@ step_bsearch_cmp(const void *a, const void *b)
 }
 
 /*
+ * If a step caused an error to be reported, print it out and clear it.
+ */
+static void
+report_error_message(Step *step)
+{
+	if (step->errormsg)
+	{
+		fprintf(stdout, "%s\n", step->errormsg);
+		free(step->errormsg);
+		step->errormsg = NULL;
+	}
+}
+
+/*
+ * As above, but reports messages possibly emitted by two steps.  This is
+ * useful when we have a blocked command awakened by another one; we want to
+ * report both messages identically, for the case where we don't care which
+ * one fails due to a timeout such as deadlock timeout.
+ */
+static void
+report_two_error_messages(Step *step1, Step *step2)
+{
+	char *prefix;
+
+	prefix = malloc(strlen(step1->name) + strlen(step2->name) + 2);
+	sprintf(prefix, "%s %s", step1->name, step2->name);
+
+	if (step1->errormsg)
+	{
+		fprintf(stdout, "error in steps %s: %s\n", prefix,
+				step1->errormsg);
+		free(step1->errormsg);
+		step1->errormsg = NULL;
+	}
+	if (step2->errormsg)
+	{
+		fprintf(stdout, "error in steps %s: %s\n", prefix,
+				step2->errormsg);
+		free(step2->errormsg);
+		step2->errormsg = NULL;
+	}
+}
+
+/*
  * Run one permutation
  */
 static void
@@ -448,17 +492,32 @@ run_permutation(TestSpec * testspec, int nsteps, Step ** steps)
 			/* Some other step is already waiting: just block. */
 			try_complete_step(step, 0);
 
-			/* See if this step unblocked the waiting step. */
+			/*
+			 * See if this step unblocked the waiting step; report both error
+			 * messages together if so.
+			 */
 			if (!try_complete_step(waiting, STEP_NONBLOCK | STEP_RETRY))
+			{
+				report_two_error_messages(step, waiting);
 				waiting = NULL;
+			}
+			else
+				report_error_message(step);
+		}
+		else
+		{
+			if (try_complete_step(step, STEP_NONBLOCK))
+				waiting = step;
+			report_error_message(step);
 		}
-		else if (try_complete_step(step, STEP_NONBLOCK))
-			waiting = step;
 	}
 
 	/* Finish any waiting query. */
 	if (waiting != NULL)
+	{
 		try_complete_step(waiting, STEP_RETRY);
+		report_error_message(waiting);
+	}
 
 	/* Perform per-session teardown */
 	for (i = 0; i < testspec->nsessions; i++)
@@ -505,6 +564,10 @@ run_permutation(TestSpec * testspec, int nsteps, Step ** steps)
  * When calling this function on behalf of a given step for a second or later
  * time, pass the STEP_RETRY flag.  This only affects the messages printed.
  *
+ * If the connection returns an error, the message is saved in step->errormsg.
+ * Caller should call report_error_message shortly after this, to have it
+ * printed and cleared.
+ *
  * If the STEP_NONBLOCK flag was specified and the query is waiting to acquire
  * a lock, returns true.  Otherwise, returns false.
  */
@@ -579,9 +642,19 @@ try_complete_step(Step *step, int flags)
 				printResultSet(res);
 				break;
 			case PGRES_FATAL_ERROR:
+				if (step->errormsg != NULL)
+				{
+					printf("WARNING: this step had a leftover error message\n");
+					printf("%s\n", step->errormsg);
+				}
 				/* Detail may contain xid values, so just show primary. */
-				printf("%s:  %s\n", PQresultErrorField(res, PG_DIAG_SEVERITY),
-					   PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY));
+				step->errormsg = malloc(5 +
+										strlen(PQresultErrorField(res, PG_DIAG_SEVERITY)) + 
+										strlen(PQresultErrorField(res,
+																  PG_DIAG_MESSAGE_PRIMARY)));
+				sprintf(step->errormsg, "%s:  %s",
+						PQresultErrorField(res, PG_DIAG_SEVERITY),
+						PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY));
 				break;
 			default:
 				printf("unexpected result status: %s\n",
diff --git a/src/test/isolation/isolationtester.h b/src/test/isolation/isolationtester.h
index 377c10c393c..1e286df596a 100644
--- a/src/test/isolation/isolationtester.h
+++ b/src/test/isolation/isolationtester.h
@@ -31,6 +31,7 @@ struct Step
 	int			session;
 	char	   *name;
 	char	   *sql;
+	char	   *errormsg;
 };
 
 typedef struct
diff --git a/src/test/isolation/specparse.y b/src/test/isolation/specparse.y
index 47bfbc4f399..b4db2f00029 100644
--- a/src/test/isolation/specparse.y
+++ b/src/test/isolation/specparse.y
@@ -123,6 +123,7 @@ step:
 				$$ = malloc(sizeof(Step));
 				$$->name = $2;
 				$$->sql = $3;
+				$$->errormsg = NULL;
 			}
 		;