localrepo: reset _phasesdirty flag after writing

mercurial/localrepo.py

@@ -949,6 +949,7 b' class localrepository(repo.repository):'
             self.store.write()
             if self._dirtyphases:
                 phases.writeroots(self)
+                self._dirtyphases = False
             for k, ce in self._filecache.items():
                 if k == 'dirstate':
                     continue