[horde] head update and now can't log in

[Craig White]

updated head today and now, when I try to login, it just returns me back
to login screen - no evidence of attempt is logged in maillog.

If I go to horde/imp/test.php, and test login, it clearly works.

So I saved horde/imp/servers.php, and edited a new copy from
servers.php.dist and still the same thing.

Any clues where I should be looking for this?

Craig