fix test-permissions output

tests/test-permissions

@@ -14,4 +14,4 @@ chmod -w .hg/store/data/a.i
 echo barber > a
 hg commit -m "2" -d "1000000 0" 2>/dev/null || echo commit failed
 chmod -w ../t
-hg diff
+hg diff --nodates

tests/test-permissions.out

@@ -14,3 +14,9 @@ crosschecking files in changesets and manifests
 checking files
 1 files, 1 changesets, 1 total revisions
 commit failed
+diff -r c1fab96507ef a
+--- a/a
++++ b/a
+@@ -1,1 +1,1 @@ foo
+-foo
++barber