[PATCH, svnmerge] Avoid hitting comand line limits

[Giovanni Bajo <ra...@develer.com>]

Hello,

one user reported a problem. He uses svnmerge to maintain a large branch
with many cherry-picks. His svnmerge-integrated property is very long and
svnmerge eventually broke: it couldn't invoke "svn propset" anymore because
of command line length limits.

This patch fixes the problem by writing the property to a temporary file,
and calling "svn propset" with -F. We use the new tempfile.mkstemp() which
is free of race-conditions, and fallback to tempfile.mktemp() when running
with Python before 2.4. Not that I expect a race condition to be a problem
here...

Committed as r18011.

[[[
Set properties using "-F" and a temporary file to avoid hitting command
line length limits.

* contrib/client-side/svnmerge.py:
  (_run_propset): New.
  (set_merge_props, set_blocked_revs): Use _run_propset.
]]]
-- 
Giovanni Bajo