tests: de-flake test-narrow-debugrebuilddirstate.t

If the dirstate gets written much later (usually 1-2 s, depending on
FS) than the working copy file (there's only one), then the `hg
debugdirstate` command will include a timestamp. There's nothing wrong
with that, so we should just allow it.

Differential Revision: https://phab.mercurial-scm.org/D4758

tests/test-narrow-debugrebuilddirstate.t

@@ -21,8 +21,8 b''
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cd copy
 
-  $ hg debugdirstate
-  n *         20 unset               foo/bar (glob)
+  $ hg debugdirstate --no-dates
+  n *         20 *               foo/bar (glob)
   $ mv .hg/dirstate .hg/old_dirstate
   $ dd bs=40 count=1 if=.hg/old_dirstate of=.hg/dirstate 2>/dev/null
   $ hg debugdirstate