Interestingly, the other way round works...

Actually, this seems to work on the SVN version.

http://192.168.0.190/wiki/Special:Code/MediaWiki/author/reedy

enter: /trunk/extensions/CodeReview/

We end up at http://192.168.0.190/w/index.php?path=/trunk/extensions/CodeReview/&title=Special:Code/MediaWiki&limit=50&title=Special:Code/MediaWiki/author/reedy

Still filtering by user

So that is actually fixed/invalid

Clicking a path in the list view though, ignores the filter. Which, I suppose, it should still honour?

Logged bug 26195 for the silly parameter thing.

Please let me know if you want clicking on revisions in the list to keep the filter ( I can't sensibly think atm whether it should...? )

And then we can work out whether to close this, or we need to look at fixing this other part

I don't run an svn checkout of CodeReview, but if you say the situation described in my initial comment is fixed, then I'm fine with this being closed.

Clicking a link (not pressing enter and/or submitting a form) makes me expect that I'm going to somewhere else and current filter/settings are ignored/unrelated to that.

However, the logic of other (core) Special:-pages with filters (such as RecentChanges and NewPages) - do do that. They manipulate filters mostly by links, not form elements (which is actually inefficient, since that requires multiple reloads when changing multiple settings, but that's for another bug).
Meaning, user expectation, based on the bahaviour of core Special:-pages, may be to preserve that. I can understand to choose to preserve author-filter when clicking a Path-link, even though I personally (like you) can't think why it should.

If anyone believes that it should preserve form values on links, feel free to re-open this bug.
For now closing becuase of FIXED in trunk.