obsolete: invalidate "volatile" set cache after merging marker

Adding markers to the repository might affect the set of obsolete changesets. So we
most remove the "volatile" set who rely in that data. We add two missing
invalidations after merging markers. This was caught by code change in the evolve
extensions tests.

This issues highlight that the current way to do things is a bit fragile,
however we keep things simple for stable.

mercurial/bundle2.py

@@ -1631,6 +1631,7 b' def handleobsmarker(op, inpart):'
         op.repo.ui.debug('ignoring obsolescence markers, feature not enabled')
         return
     new = op.repo.obsstore.mergemarkers(tr, markerdata)
+    op.repo.invalidatevolatilesets()
     if new:
         op.repo.ui.status(_('%i new obsolescence markers\n') % new)
     op.records.add('obsmarkers', {'new': new})

mercurial/obsolete.py

@@ -767,6 +767,7 b' def pushmarker(repo, key, old, new):'
         tr = repo.transaction('pushkey: obsolete markers')
         try:
             repo.obsstore.mergemarkers(tr, data)
+            repo.invalidatevolatilesets()
             tr.close()
             return 1
         finally: