1779: Better error messaging when running post-review on an empty change

ben.h*****@gmai***** (Google Code) (Is this you? Claim this profile.)
Aug. 30, 2010
What version are you running?
RBTools 0.2

What steps will reproduce the problem?
1. Create an empty changeset in perforce (no files or files with no changes)
2. Run post-review with the changeset number

What is the expected output? What do you see instead?
I'd expect it to give me an error saying the review was empty. Instead I get a generic error/stacktrace.