Test for bug. Current stemming support for notmuch adds extra terms
to the DB which aren't removed when the file renames are detected.
When folder tags are added to a message, Xapian terms for both XFOLDER
and ZXFOLDER are generated. When one of the filenames are
renamed/removed, only the XFOLDER tags are removed, leaving it possible
for a match on a folder: tag that was previously but is no longer a
match in the maildir.
(cherry picked from commit 86e0baeb6d)
