--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -296,16 +296,9 @@ class dirstate:
         # compare all files by default
         if not files: files = [self.root]
 
-        def uniq(g):
-            seen = {}
-            for f in g:
-                if f not in seen:
-                    seen[f] = 1
-                    yield f
-
         # recursive generator of all files listed
         def walk(files):
-            for f in uniq(files):
+            for f in util.unique(files):
                 f = os.path.join(self.root, f)
                 if os.path.isdir(f):
                     for dir, subdirs, fl in os.walk(f):
@@ -317,7 +310,7 @@ class dirstate:
                 else:
                     yield f[len(self.root) + 1:]
 
-        for fn in uniq(walk(files)):
+        for fn in util.unique(walk(files)):
             try: s = os.stat(os.path.join(self.root, fn))
             except: continue
 

--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -7,6 +7,13 @@
 
 import os
 
+def unique(g):
+    seen = {}
+    for f in g:
+        if f not in seen:
+            seen[f] = 1
+            yield f
+
 class CommandError(Exception): pass
 
 def explain_exit(code):