Fixes for version information for modules

Created originally on Bitbucket by ayshih (Albert Shih)

Changesets for this Pull Request have not been imported, because it had been already declined on Bitbucket. Marked as closed by the import user.

• Fixed hgstamp generation so that it is actually updated when necessary (before, the file needed to be deleted)
• Fixed searching for the most recent relevant commit (e.g., for module strings) so that only ancestors are looked at, rather than commits across all branches, which could be misleading