Selected menu link is sometimes wrong

I'm working on fixing bug 1809; if my merge goes through, just visit any potemplate or pofile page to notice that the selected (the one I see in bold) link is a disabled link. I don't know if this is an artifact of the hack I used to disable them or if there's something else in play there, but I wanted to file this before forgetting it.

A concrete example using the sample data is:

http://localhost:8086/products/netapplet/+series/releases/+pots/netapplet/af/+translate

The cause of the problem is that the three facet tabs, Bugs, Translations and Calendar, are all defined to have the same empty link target, and so the same URL. If you reload the page, you'll see the selected tab vary randomly between these three.

So, there is a bug in the menus system that the selected tab is not chosen deterministicly when there is some ambiguity.

I see from POFileFacets that the Bugs and Calendar tabs are supposed to be not linked, but the way this has been done in the code will not work.