Freeze break request: tweak mediawiki's fedmsg plugin

[Ralph Bean]

Good evening,

The httpd root process has been dieing seemingly at random on the
different app0* servers.  We're not sure what it is, but there's a
chance that it could be the fedmsg-emit.php plugin.  Here's a proposed
patch that's been sitting in staging for about a week:

  http://www.fpaste.org/VqpG/

The theory is that, before, if "fedmsg-config" failed (which it
shouldn't), then the script would call die().  die() shouldn't
terminate the root httpd process, but.. well.. we're not sure
what else could be happening.

The change goes:  instead of calling die(), if the plugin can't
setup its fedmsg socket, then it just won't register its callbacks
with mediawiki, instead of calling die();

I've tested that this is sane in staging, but there's no way to test
that it fixes the issue, since it happens randomishly.

This doesn't require a new fedmsg rpm.  The fedmsg-emit.php plugin
is kept in puppet.

Seeking +1s for freeze break.

Cheers!