Xbuntu / AMD
Short description of error
If you have the manipulator enabled and you deselect all the bones in pose mode it doesn't disappear.
Note: This bug was already fixed before (see T56434) but it seems to be here again.
Exact steps for others to reproduce the error
Create an armature
Go to pose mode
Enable the manipulator (by being forced to press "T" for the tools menu and selecting "Transform")
Select a bone
Press Alt+A to deselect all
...the manipulator stays there...