$.timepicker is undefined
git blame points to Bug 25133, "Fix time part of due date for 12hr"
(In reply to Owen Leonard from comment #0)
Correction: The problem appears to be on any page with a datepicker.
Seen the last follow-up on bug 25133?
The last follow-up appears to fix the issue for me - marking duplicate.
*** This bug has been marked as a duplicate of bug 25133 ***