Trying to build a test repository for the content_get problem, I see:

    fossil: ancestor check-in [400e924baf] (2010-10-04 16:29:26) is younger (clock skew?) Use -f to override.

This is wrong, because the ancestor has the same modification time as the new commit. Either the message should be "is not older" or the check should be for > and not >= in checkin.c.