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.
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
created new head
% Merging a conflict araises
merging A
warning: conflicts during merge.
merging A failed!
1 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg up --clean' to abandon
% Correct the conflict without marking the file as resolved
abort: unresolved merge conflicts (see hg resolve)
% Mark the conflict as resolved and commit