tag intersection searches e.g. /tag/foo+bar broken using default permalinks not custom

[polins]

Tag intersection (=and) searches broken:

​http://site.com/tag/foo+bar resturns the correct result only with custom permalinks setting, not the default.
The default permalinks result in ALL posts being returned, regardless of assigned tag.

However, ​http://site.com/?tag=foo+bar does work correctly.

Also:

​http://site.com/tag/foo+nonexistenttag returns ALL posts regardless of tag, again, only with the default permalink settings.
(I'm guessing that the latter issue will be addressed at WP 3.2 via Ticket #17194?)

Setup: WP 3.1.2, 2010 1.2 theme, no plugins

[scribu]

It's not really clear what the problem is, from your description.

Please post step-by-step instructions, along with expected and actual behaviour.

[scribu]

Are you suggesting that with default (ugly) permalinks, ​http://site.com/tag/foo+bar doesn't work?

If so, then yes, of course it won't work. The correct URL in that case is ​http://site.com/?tag=foo+bar as you've found out. That's why they're called ugly permalinks.

[polins]

Pardon my ignorance. Apologies for taking up your time, scribu. :~(

[scribu]

No worries. You might want to try the ​support forums first, next time.