We recently upgraded to rP62794e4494e0 from a revision that was at least a couple of months old.
Maniphest is no longer displaying tasks in descending order of priority even when "Order by: Priority" is selected in "Edit Query".
Seems like all the tasks from prior to the upgrade appear in priority order, but new tasks that are assigned to users show up in random places in that user's list of tasks ordered by priority.
I'm not sure if it always happens or only gets triggered in some particular scenario (like creating new task, or editing a task or whatever). In the latest case in our instance, I reassigned a High priority task from me to someone else, and it's appearing below Normal priority tasks in that guy's list. I think it's happening only when tasks are reassigned rather than for tasks that are assigned while being created.
Somewhat relatedly, "Group by: Assigned" combined with "Order by: Priority" now displays the users in random order. Previously the users were in alphabetical order. Don't know if it was a coincidence, but it was certainly very useful.