buildbot/buildbot — pull request #1326 by delanne (2014-11-05 15:23:38+00:00)
Title:  - Fix PeriodicScheduler when a build is triggered with no changes

when the PeriodicScheduler trigger a build with no changes, we have this traceback:
```
Traceback (most recent call last):
Failure: twisted.internet.defer.FirstError: FirstError[#0, [Failure instance: Traceback: : project cannot be None
/home/xavierd/Projects/myGitHub/buildbot-work/sandbox/local/lib/python2.7/site-packages/twisted/internet/defer.py:1099:_inlineCallbacks
/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/db/buildsets.py:60:addBuildset
/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/db/buildsets.py:58:toSsid
/home/xavierd/Projects/myGitHub/buildbot-work/sandbox/local/lib/python2.7/site-packages/twisted/internet/defer.py:1237:unwindGenerator
--- ---
/home/xavierd/Projects/myGitHub/buildbot-work/sandbox/local/lib/python2.7/site-packages/twisted/internet/defer.py:1099:_inlineCallbacks
/home/xavierd/Projects/myGitHub/buildbot-work/src/master/buildbot/db/sourcestamps.py:45:findSourceStampId
]]
```