rollback: clear resolve state (issue4593)

mercurial/localrepo.py

@@ -1092,6 +1092,9 b' class localrepository(object):'
             else:
                 ui.status(_('working directory now based on '
                             'revision %d\n') % parents)
+            ms = mergemod.mergestate(self)
+            ms.reset(self['.'].node())
+
         # TODO: if we know which new heads may result from this rollback, pass
         # them to destroy(), which will prevent the branchhead cache from being
         # invalidated.