BUG/MINOR: http-ana: Throw a 500 error if after-response ruleset fails on errors

BUG/MINOR: http-ana: Throw a 500 error if after-response ruleset fails on errors

It is the intended behaviour. But because of a bug, the 500 error resulting of a
rewrite failure during http-after-response ruleset evaluation is also
rewritten. So if at this step, if there is also a rewrite error, the session is
closed and no error message is returned.

Instead, we must be sure to not evaluate the http-after-response rules on an
error message if it is was thrown because of a rewrite failure on a previous
error message.

It is a 2.2-dev2+ bug. No need to backport. This patch should fix the issue