Caused by rBe07b245fe1f4 (new 'Select Linked' posemode op).
Above commit took CTRL+L (and this is kept for consistency with other
'Select Linked' operators).
So now keymap for poselib is:
poselib browse: ALT+L (was CTRL+L -- conflict here)
poselib add pose: SHIFT+L (same as before)
poselib remove pose: SHIFT+ALT+L (was ALT+L)
poselib rename pose: SHIFT+CTRL+L (same as before)
ref. D7542
18dbc8f5c1