t5561: get rid of racy appending to logfile

t5561: get rid of racy appending to logfile

The definition of log_div() appended information to the web server's
logfile to make the test more readable. However, log_div() was called
right after a request is served (which is done by git-http-backend);
the web server waits for the git-http-backend process to exit before
it writes to the log file. When the duration between serving a request
and exiting was long, the log_div() output was written before the last
request's log, and the test failed. (This duration could become
especially long for PROFILE=GEN builds.)

To get rid of this behavior, we should not change the logfile at all.
This commit removes log_div() and its calls. The additional information
is kept in the test (for readability reasons) but filtered out before
comparing it to the actual logfile.

Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>