localrepo._tag: add a seek before writing the new tag
Some systems require a seek (or flush) between read and write
operations on the same file object.
This should fix issue838.
#!/usr/bin/env python
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
# enable importing on demand to reduce startup time
from mercurial import demandimport; demandimport.enable()
import mercurial.dispatch
mercurial.dispatch.run()