setup.py: fix version detection for tarball - don't do version detection if there's no .hg directory - shrink try: clause - don't write __version__.py if version is unknown (we might overwrite the real version)

adding a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
tip                                3:a49829c4fc11
t1                                 0:f7b1eb17ad24