For a large perforce server with many users, this allows projects
to opt-in to zulip notifications by creating the stream for the
branch to be monitored.
Commits to paths for which a stream mapping yields a result,
but no stream exists in Zulip, are simply dropped silently.
This behaviour is opt-in, by setting the configuration key
ZULIP_IGNORE_MISSING_STREAM = True
in the zulip_perforce_config.py file.
The general regex-based linkify in zulip does not allow '@' as the
prefix. In any case we know here that it is definitely a changelist
number, which is better.
Adding P4_WEB="https://p4web.example.com" to the config will enable
this behaviour. If P4_WEB is absent from the config, or has the
value None, no link is inserted.
This is designed to be run as a "change-commit" trigger. See [Perforce's
documentation][1] on how to set up a trigger for your platform.
[1]: http://www.perforce.com/perforce/r12.1/manuals/cmdref/triggers.html
Closes trac #1034.
(imported from commit d94fa4e50637ade2847a96eab8c5514de3811c24)
