pantsbuild/pants — pull request #464 by mateor (2014-08-10 22:46:20+00:00)
Title: Add a try/raise to catch exception from calling os on None object

If someone defines an Android target without specifying a 'manifest'
field in the BUILD file, they only got a cryptic error. The exception was
never called because the error came earlier, when calling os.path on a None
object. This ensures that the user sees the error message we mean them to.