diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -80,9 +80,24 @@ def itersubrepos(ctx1, ctx2):
     # has been modified (in ctx2) but not yet committed (in ctx1).
     subpaths = dict.fromkeys(ctx2.substate, ctx2)
     subpaths.update(dict.fromkeys(ctx1.substate, ctx1))
+
+    missing = set()
+
+    for subpath in ctx2.substate:
+        if subpath not in ctx1.substate:
+            del subpaths[subpath]
+            missing.add(subpath)
+
     for subpath, ctx in sorted(subpaths.iteritems()):
         yield subpath, ctx.sub(subpath)
 
+    # Yield an empty subrepo based on ctx1 for anything only in ctx2.  That way,
+    # status and diff will have an accurate result when it does
+    # 'sub.{status|diff}(rev2)'.  Otherwise, the ctx2 subrepo is compared
+    # against itself.
+    for subpath in missing:
+        yield subpath, ctx2.nullsub(subpath, ctx1)
+
 def nochangesfound(ui, repo, excluded=None):
     '''Report no changes for push/pull, excluded is None or a list of
     nodes excluded from the push/pull.
diff --git a/tests/test-mq-subrepo.t b/tests/test-mq-subrepo.t
--- a/tests/test-mq-subrepo.t
+++ b/tests/test-mq-subrepo.t
@@ -106,6 +106,7 @@ handle subrepos safely on qnew
   [255]
   % update substate when adding .hgsub w/clean updated subrepo
   A .hgsub
+  A sub/a
   % qnew -X path:no-effect -m0 0.diff
   path sub
    source   sub
@@ -121,6 +122,7 @@ handle subrepos safely on qnew
   [255]
   % update substate when modifying .hgsub w/clean updated subrepo
   M .hgsub
+  A sub2/a
   % qnew --cwd .. -R repo-2499-qnew -X path:no-effect -m1 1.diff
   path sub
    source   sub
@@ -165,6 +167,7 @@ handle subrepos safely on qrefresh
   [255]
   % update substate when adding .hgsub w/clean updated subrepo
   A .hgsub
+  A sub/a
   % qrefresh
   path sub
    source   sub
@@ -181,6 +184,7 @@ handle subrepos safely on qrefresh
   [255]
   % update substate when modifying .hgsub w/clean updated subrepo
   M .hgsub
+  A sub2/a
   % qrefresh
   path sub
    source   sub
@@ -304,6 +308,7 @@ handle subrepos safely on qrecord
   [255]
   % update substate when adding .hgsub w/clean updated subrepo
   A .hgsub
+  A sub/a
   % qrecord --config ui.interactive=1 -m0 0.diff
   diff --git a/.hgsub b/.hgsub
   new file mode 100644
@@ -339,6 +344,7 @@ handle subrepos safely on qrecord
   [255]
   % update substate when modifying .hgsub w/clean updated subrepo
   M .hgsub
+  A sub2/a
   % qrecord --config ui.interactive=1 -m1 1.diff
   diff --git a/.hgsub b/.hgsub
   1 hunks, 1 lines changed
diff --git a/tests/test-subrepo.t b/tests/test-subrepo.t
--- a/tests/test-subrepo.t
+++ b/tests/test-subrepo.t
@@ -1703,4 +1703,37 @@ Test that '[paths]' is configured correc
   [paths]
   default = $TESTTMP/t/t
   default-push = /foo/bar/t
+
+  $ cd $TESTTMP/t
+  $ hg up -qC 0
+  $ echo 'bar' > bar.txt
+  $ hg ci -Am 'branch before subrepo add'
+  adding bar.txt
+  created new head
+  $ hg merge -r "first(subrepo('s'))"
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg status -S -X '.hgsub*'
+  A s/a
+  ? s/b
+  ? s/c
+  ? s/f1
+  $ hg status -S --rev 'p2()'
+  A bar.txt
+  ? s/b
+  ? s/c
+  ? s/f1
+  $ hg diff -S -X '.hgsub*' --nodates
+  diff -r 000000000000 s/a
+  --- /dev/null
+  +++ b/s/a
+  @@ -0,0 +1,1 @@
+  +a
+  $ hg diff -S --rev 'p2()' --nodates
+  diff -r 7cf8cfea66e4 bar.txt
+  --- /dev/null
+  +++ b/bar.txt
+  @@ -0,0 +1,1 @@
+  +bar
+
   $ cd ..