work around python bug on solaris 10.
write to file opened mode 'a+' should write to end of file and update
offset pointer, but does not (solaris 10 has python 2.3.3).
fix is to always seek.
# repo.py - repository base classes for mercurial
#
# Copyright 2005 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.
class RepoError(Exception): pass