Mike Edgar <adgar@google.com> [Mon, 15 Sep 2014 16:07:54 -0400] rev 22446
contrib/synthrepo: return None to delete files on commit, don't raise IOError
The internal commit API was changed in 650b5b6e75ed to expect None from the
filectx function when a file is to be deleted, not an IOError. This change
keeps synthrepo up-to-date.