bug#49115: Mumi inserts spurious underscore in bug title

[Ricardo Wurmus]

Hi Arun,

> Thanks for the bug report!
>
> It's very strange, but I'm not able to reproduce this.

Thank you for your analysis!

> Even at https://issues.guix.gnu.org/49114 , only the "bug title" has the
> spurious underscore. The subject of the first message does not. Is the
> bug title something stored in the xapian index? Could it be that this
> was an older bug that has corrupted the xapian index?

As part of #60410 I rebuilt the xapian database (deleted it and then ran
“mumi fetch”), so it’s not that.

[… time passes …]

I think I found the culprit in mumi/debbugs.scm:

    (define qp-pattern "=\\?UTF-8\\?Q\\?([^?]+)\\?=")
    …
    (let ((subject (or (assoc-ref properties "Subject") "")))
      (if (string-contains subject "=?UTF-8?Q?")
          (or (false-if-exception
               (utf8->string
                (quoted-printable-decode
                 (regexp-substitute/global #f qp-pattern
                                           subject 'pre 1 'post))))
              subject)
          subject))

I’m probably not using quoted-printable-decode correctly.  My apologies
for assuming a bug in Guile Email.  I changed this with commit
9d7eb3c5efe6427a1a89fb3e4c7165259edff4dd, using parse-email-headers.

> If I understand correctly, mumi does not rebuild its xapian index. I
> think it should do so from time to time. It would help prevent old bugs
> from getting persisted in storage.

True.  I’ll be sure to rebuild the index on the next upgrade.

> Cheers, and wish you a Happy New Year! :-)

Thank you, and a Happy New Year to you too!

-- 
Ricardo