Punctuation confuses bug search?

[Don Kirkby]

I'm not sure of the cause, but it may be that when a bug title contains a search term surrounded by punctuation, it is not included in the search results.
Here's an example:
I ran a bug search in Launchpad itself for the terms "RSS Mailing lists".
I expected to find bug 317453 that has the summary, "Atom (/RSS?) feeds of Mailing lists".
Only one bug appeared in the search results: bug 577217, "Notify translators when new strings are imported".

Here's a link to the example search:
https://bugs.launchpad.net/launchpad/+bugs?field.searchtext=RSS+Mailing+lists

If I search for "Atom" instead of "RSS", it works:
https://bugs.launchpad.net/launchpad/+bugs?field.searchtext=Atom+Mailing+lists

If I search for the exact punctuation, it still doesn't find the bug I'm looking for:
https://bugs.launchpad.net/launchpad/+bugs?field.searchtext=(/RSS?)+Mailing+lists

If I edit the title of bug 317453 to remove the punctuation, it then appears in the search results. The new title is, "Atom or RSS feeds of Mailing lists".

[Don Kirkby (donkirkby)]

I don't think this is a duplicate of bug 780636. That bug says that basic search does not include tags. This bug is that search does not find a search term if it's surrounded by punctuation.
I just found a bit more information: if I edit the title of bug 317453 to remove the punctuation, it then appears in the search results.