darcs+buildbot postcommit hook doesn't report tags

[warner]

The darcs_buildbot.py post-commit hook doesn't send a Change object to the buildmaster when a tag is pushed into the repository. As a result, the buildbot doesn't automatically build .debs of released versions, only of intermediate versions. This is a pity, because it would be nice for us to have packages of official releases.

I'm not sure what is necessary to fix this: I seem to recall that tags in darcs are handled very differently than regular patches, so the 'apply' action might not be enough to catch both. On the other hand, it might just be that the darcs_buildbot.py script (which is run by the apply action) is deficient, perhaps exiting if it sees no files changed when it should send a Change anyway.