strange tagging in git results in unusable version

[birkenfeld]

When you do strange things like lightweight-tagging an annotated tag object, you get output from git describe like so:

$ git describe --tags --abbrev=0
warning: tag '1.0.0' is really 'v1.0.0' here
1.0.0

tar_scm currently just takes this whole output, including the newline, as the parent tag, which is suboptimal.

The warning is printed to stderr, so it would seem to be better not to use stderr=STDOUT in the subprocess call. Alternatively, error out in these cases.

[aspiers]

Yes I agree; thanks for the report. PRs welcome.