Revert "BUG/MINOR: master/cli: properly trim the '@@' process name in error messages"

Revert "BUG/MINOR: master/cli: properly trim the '@@' process name in error messages"

This reverts commit 0e94339eaf1c8423132debb6b1b485d8bb1bb7da.

This patch was in fact fixing the symptom, not the cause. The root cause
of the problem is that the parser was processing an incomplete line when
looking for '@@'. When the LF is present, this problem does not exist
as it's properly replaced with a zero. This can be verified using socat
in raw mode:

  socat /tmp/master.sock STDIO,raw,echo=0

Then entering "@@1 show info" one character at a time will immediately
fail on "@@" without going further. A subsequent patch will fix this.
No backport is needed.