inhibit: add test to ensure that --hidden is working with inhibit There was a concern with the transaction hook in inhibit and its potentially devastating effect when used with --hidden. The transaction hook in inhibit hides all the visible & obsolete commits when the transaction ends using the visible() and the obsolete() revset. --hidden does not change the visible() revset so it is fine. If this changes in the future and --hidden actually ends up impacting the visible() revset, this test will catch it and prevent inhibit from putting inhibition markers on all of the obsolete changesets.