Before this commit, if comments were found inside the body of a mail
template sent through mass_mailing, the regex in append_content_to_html
that converts possible uppercase tags to lowercase tags would replace
comments by broken html elements, this would break the in-browser parser
and thus would show partial content or no content at all, depending on
the positioning of the comments.
i.e. from <!-- This is a comment --> to <this -->
The regex in question is r'(</?)\W*(\w+)([ >])' which basically matches
opening and closing tags (this was a bad idea from the beginning btw),
the \W* will match any non-alphanumeric chars (so !-- in the
case of comments) and this would be completely discarded since it's not
a match group and when replacing we only use match groups.
This is fixed by simply stripping the \W* since it's discarded anyway,
an alternative fix would be to put it in a match group and add it when
replacing as well, but I don't know if we purposefully discard it or
not.
Neither fix is the good one, the good fix is to replace all the re.subs
by lxml which is much easier and more concise.
Adrian Torres
2f0435f081