Failure to "bzr merge -r X..Y filename" on Windows

This is indeed about leaving files around without closing them, with filehack I get this:

Unclosed file: u'%TMP%/testbzr-dwm89j.tmp/_merge_reversed_revision_range/work/a'
  File ".\bzrlib\commands.py", line 1140, in run_bzr_catch_user_errors
    return run_bzr(argv)
  File ".\bzrlib\commands.py", line 1038, in run_bzr
    ret = run(*run_argv)
  File ".\bzrlib\commands.py", line 655, in run_argv_aliases
    return self.run(**all_cmd_args)
  File ".\bzrlib\builtins.py", line 3692, in run
    possible_transports=possible_transports)
  File ".\bzrlib\bundle\__init__.py", line 49, in read_mergeable_from_url
    _do_directive)
  File ".\bzrlib\bundle\__init__.py", line 71, in read_mergeable_from_transport
    redirected_transport)
  File ".\bzrlib\transport\__init__.py", line 1644, in do_catching_redirections
    return action(transport)
  File ".\bzrlib\bundle\__init__.py", line 59, in get_bundle
    return transport.get(filename), transport
  File ".\bzrlib\transport\local.py", line 163, in get
    return open(path, 'rb')

Have a fix for this I'll post shortly.

Merged in r4853 - this bug probably wants the milestone setting to something too but I don't see how.