compat-test: merge with stable

test-compat: fix previous merge The merge was a bit too heavy handed in dropping some part of the test.

merge with default Integrate new development around obsfate.

obsfate: by default only display the username if differ from the current one This will will keep the output simple in the simple case.

obsfate: display more data about direct prune markers This does not handle all cases, but this should handle the most common ones.

obsfate: split markers fetch from successor set annotation This will help to improve support for pruned changesets.

obsfate: mark successorsetallmarkers public We are about to use it in another module.

obsfate: mark 'preparesuccessorset' as public It is used in another module so it is not really private.

obsfate: use 'split' as verb when appropriate

obsfate: improve prune support in _successorsetverb In the prune case, still have markers (at least the prune markers). If we want to be able to return these markers we need the underlying function to support it.