patchbomb: fix stray backslash in docstring
While both '\ ' and '\\ ' parse the same in Python, the difference
trips up hggettext so that it cannot find the docstring in the source
file and thus cannot write the right line number to i18n/hg.pot.
While the line number is not essential, it can be used to lookup the
original message.
(binary:application/octet-stream)