[ews-build] Gracefully handle missing patch_id in events

[Aakash Jain]

If the patch_id is missing in a build, following exception is generated while generate events. We should handle it gracefully.

2019-03-25 14:10:02-0700 [-] while invoking <bound method Events.buildFinished of <events.Events object at 0x7fc1a2c8d210>>
	Traceback (most recent call last):
	  File "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 393, in callback
	    self._startRunCallbacks(result)
	  File "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 501, in _startRunCallbacks
	    self._runCallbacks()
	  File "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 587, in _runCallbacks
	    current.result = callback(current.result, *args, **kw)
	  File "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 1241, in gotResult
	    _inlineCallbacks(r, g, deferred)
	--- <exception caught here> ---
	  File "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 1185, in _inlineCallbacks
	    result = g.send(result)
	  File "events.py", line 148, in buildFinished
	    "patch_id": self.getPatchID(build),
	  File "events.py", line 106, in getPatchID
	    return build.get('properties').get('patch_id')[0]
	exceptions.TypeError: 'NoneType' object has no attribute '__getitem__'

[Aakash Jain]

Created attachment 365899 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 365899 [details]
Patch

Clearing flags on attachment: 365899

Committed r243464: <https://trac.webkit.org/changeset/243464>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/49231513>