Problem with mq extension - qpop then qpush fails

[Paul Moore]

I'm having trouble with (what I think is) a fairly simple use of mq.
The sequence of events is:

1. I have a Mercurial repository that's up to date.
2. hg qinit
3. hg qnew codepage
4. Edit Lua.c
5. hg qrefresh

-- at this point, hg diff shows the changes in the "codepage" patch.

6. hg qtop
   codepage

7. hg qpop
   Patch queue now empty

8. hg qpush
   applying codepage
   patch failed, unable to continue (try -v)
   No username found, using 'UK03306 at UK004134.uk.int.atosorigin.com' instead
   patch failed, rejects left in working dir
   Errors during apply, please fix and refresh codepage

9. hg qpush -v
   abort: patch series fully applied

I thought qpop followed by qpush should leave things unchanged???

I've probably missed something, but I've tried to follow the tutorial
and documents on the wiki.

Thanks for any help.
Paul.