bookmarks backend needs to be choosier

[Edd Dumbill <edd usefulinc com>]

So, an email I received has the character sequence '#9' in it.  The
textchainer sent this as a bugzilla clue.  Then bookmarks picked out
every single bookmark of mine with the character '9' in it.

Bookmarks should probably not listen to bugzilla clues.

-- Edd