diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -10,7 +10,7 @@ from i18n import _
 import os, sys, errno, re, glob, tempfile
 import util, templater, patch, error, encoding, templatekw
 import match as matchmod
-import similar, revset
+import similar, revset, subrepo
 
 revrangesep = ':'
 
@@ -683,14 +683,7 @@ def diffordiffstat(ui, repo, diffopts, n
     if listsubrepos:
         ctx1 = repo[node1]
         ctx2 = repo[node2]
-        # Create a (subpath, ctx) mapping where we prefer subpaths
-        # from ctx1. The subpaths from ctx2 are important when the
-        # .hgsub file has been modified (in ctx2) but not yet
-        # committed (in ctx1).
-        subpaths = dict.fromkeys(ctx2.substate, ctx2)
-        subpaths.update(dict.fromkeys(ctx1.substate, ctx1))
-        for subpath, ctx in subpaths.iteritems():
-            sub = ctx.sub(subpath)
+        for subpath, sub in subrepo.itersubrepos(ctx1, ctx2):
             if node2 is not None:
                 node2 = bin(ctx2.substate[subpath][1])
             submatch = matchmod.narrowmatcher(subpath, match)
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1161,14 +1161,7 @@ class localrepository(repo.repository):
         r = modified, added, removed, deleted, unknown, ignored, clean
 
         if listsubrepos:
-            # Create a (subpath, ctx) mapping where we prefer subpaths
-            # from ctx1. The subpaths from ctx2 are important when the
-            # .hgsub file has been modified (in ctx2) but not yet
-            # committed (in ctx1).
-            subpaths = dict.fromkeys(ctx2.substate, ctx2)
-            subpaths.update(dict.fromkeys(ctx1.substate, ctx1))
-            for subpath, ctx in subpaths.iteritems():
-                sub = ctx.sub(subpath)
+            for subpath, sub in subrepo.itersubrepos(ctx1, ctx2):
                 if working:
                     rev2 = None
                 else:
diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -184,6 +184,16 @@ def _abssource(repo, push=False):
         return repo.ui.config('paths', 'default-push', repo.root)
     return repo.ui.config('paths', 'default', repo.root)
 
+def itersubrepos(ctx1, ctx2):
+    """find subrepos in ctx1 or ctx2"""
+    # Create a (subpath, ctx) mapping where we prefer subpaths from
+    # ctx1. The subpaths from ctx2 are important when the .hgsub file
+    # has been modified (in ctx2) but not yet committed (in ctx1).
+    subpaths = dict.fromkeys(ctx2.substate, ctx2)
+    subpaths.update(dict.fromkeys(ctx1.substate, ctx1))
+    for subpath, ctx in sorted(subpaths.iteritems()):
+        yield subpath, ctx.sub(subpath)
+
 def subrepo(ctx, path):
     """return instance of the right subrepo class for subrepo in path"""
     # subrepo inherently violates our import layering rules