idirstate: add missing get_entry() method

Differential Revision: https://phab.mercurial-scm.org/D12566

mercurial/interfaces/dirstate.py

@@ -61,6 +61,9 class idirstate(interfaceutil.Interface)
         used to get real file paths. Use vfs functions instead.
         """
 
+    def get_entry(path):
+        """return a DirstateItem for the associated path"""
+
     def pathto(f, cwd=None):
         pass