Runahead limit not updated after cylc remove

[hjoliver]

[scheduling]
   cycling mode = integer
   [[graph]]
       P1 = "a => b => c"
[runtime]
   [[b]]
       script = false
   [[a, c]]

Run till stalled with 1,2,3,4,5/b failed.

• cylc remove bug//1/b:failed removes 1/b but the scheduler stays stalled and does not release 6/b from runahead
• cylc remove bug//*/b:failed removes all failed b and the scheduler shuts down (no tasks released from runahead)