Ensure github change body is not a NoneType

The test framework was already operating in this way, but this changes
it to reflect that we might get pull requests without a body
(description). Without this, we'd attempt to run a regex on a None type
which causes a traceback.

Change-Id: Ibabf6452bd7d0c6df071227d8a3dc2e32f36158e
2 files changed