notify: do not mime encode multipart templates
Mulitpart templates should take care of this themselves.
See http://www.selenic.com/pipermail/mercurial/2009-July/027017.html
Also catch potential parsing errors gracefully.
foo renamed from bar:26d3ca0dfd18e44d796b564e38dd173c9668d3a9
rev offset length base linkrev nodeid p1 p2
0 0 6 0 0 26d3ca0dfd18 000000000000 000000000000
1 6 7 1 1 d267bddd54f7 26d3ca0dfd18 000000000000