family.py: bump refuses a --to that names an annotated tag, a tree or a blob as member-to-not-a-commit before the checkout, naming the commit a tag names, and its dry run refuses alike, so a release tag's own id no longer exits 0 with a commit pinning the tag over a gitlink at its commit, which the holder's validate-family.py refused as member-gitlink-mismatch (#405) - #466