dirstate-map: factor out the change to _dirs and _alldirs on adding

This logic is complicated enough to deserves its own function. So it now does.

This will make it easier to reuse that logic in later changeset.

Differential Revision: https://phab.mercurial-scm.org/D11129

mercurial/dirstatemap.py

@@ -146,6 +146,15 b' class dirstatemap(object):'
         """Loads the underlying data, if it's not already loaded"""
         self._map
 
+    def _dirs_incr(self, filename, old_entry=None):
+        """incremente the dirstate counter if applicable"""
+        if (
+            old_entry is None or old_entry.removed
+        ) and "_dirs" in self.__dict__:
+            self._dirs.addpath(filename)
+        if old_entry is None and "_alldirs" in self.__dict__:
+            self._alldirs.addpath(filename)
+
     def addfile(
         self,
         f,
@@ -190,12 +199,7 b' class dirstatemap(object):'
         assert size is not None
         assert mtime is not None
         old_entry = self.get(f)
-        if (
-            old_entry is None or old_entry.removed
-        ) and "_dirs" in self.__dict__:
-            self._dirs.addpath(f)
-        if old_entry is None and "_alldirs" in self.__dict__:
-            self._alldirs.addpath(f)
+        self._dirs_incr(f, old_entry)
         e = self._map[f] = DirstateItem(state, mode, size, mtime)
         if e.dm_nonnormal:
             self.nonnormalset.add(f)