advanced search for an assignee does not produce correct results

[Lee Bieber]

I ran a query looking for bugs assigned to posulliv

https://bugs.launchpad.net/drizzle/+bugs?field.searchtext=&orderby=-importance&search=Search&field.status%3Alist=NEW&field.status%3Alist=INCOMPLETE_WITH_RESPONSE&field.status%3Alist=INCOMPLETE_WITHOUT_RESPONSE&field.status%3Alist=CONFIRMED&field.status%3Alist=TRIAGED&field.status%3Alist=INPROGRESS&field.status%3Alist=FIXCOMMITTED&assignee_option=any&field.assignee=posulliv&field.bug_reporter=&field.bug_supervisor=&field.bug_commenter=&field.subscriber=&field.tag=&field.tags_combinator=ANY&field.has_cve.used=&field.omit_dupes.used=&field.omit_dupes=on&field.affects_me.used=&field.has_patch.used=&field.has_branches.used=&field.has_branches=on&field.has_no_branches.used=&field.has_no_branches=on

but only got back 4 bugs 646898, 560489, 639716, 522423. . That is not correct as https://bugs.launchpad.net/drizzle/+bug/628397 is assigned to posulliv. I know there are others also assigned to posulliv.

[Robert Collins (lifeless)]

This was a case of onlyseriesbugtasks cropping up - the inverse of bug 423692. I'm going to dup on that and make it cover both sides.