When a non-existent Gluster volume is to be deleted, i.e.:
gluster_volume:
state: absent
name: vol1-does-not-exist
the "gluster_volume" module would always fail with "volume not found
vol1-does-not-exist". The reason is that the code checked whether the
state is "delete", a value which isn't accepted for the "state"
parameter. Instead the expected value for volume deletion is, as above,
"absent".