test-obsolete-bundle-strip: check all changesets in the isolated prune case We also want to check the result of the various computations when both changesets are selected (the pruned changesets and its parents).

test-obsolete-bundle-strip: add testing of markers backup during strip When applicable, we strip the revision tested in the test and we check that the backup bundle contains the appropriate markers.

strip: also backup obsmarkers We are about to give 'strip' the ability to remove obsmarkers. Before we start removing data we must make sure it is preserved somewhere. So the backup bundle created by 'strip' now contains obsmarkers.