parsers: rewrite index_ancestors() in terms of index_commonancestorsheads()
The first 80% of index_ancestors() is identical to
index_commonancestorsheads(), so just call that function instead.
fixbundle() { grep -v 'saving bundle' | grep -v 'saved backup' | \ grep -v added | grep -v adding | \ grep -v "unable to find 'e' for patching" | \ grep -v "e: No such file or directory"}