Review of the previous commit caught that its docstring promised more
than the code did. Not restarting an *open* window still let a progress
that flapped out of and back into Finish re-arm a full fresh window once
the first had expired, so the value could be held well past
sticky_seconds from the first Finish. The new test passed only because
its final read left the sticky condition matching; ending the flap on a
non-matching read re-armed and would have failed it.
Make the guarantee real instead of weakening the claim: arming marks the
hold spent, and only sticky_bypass_fn -- a cycle actually running --
clears it. Expiry on its own no longer re-opens the door, because with no
cycle in between a second Finish is the same Finish, and re-arming on it
strobes the entity Finish -> Idle -> Finish once per window, re-firing
the announcements #345 and #358 are both about.
That subsumes the old _sticky_armed edge-trigger flag, which existed to
stop a stuck field extending the window; "spent until a new cycle" covers
that case and the flap case together, before or after expiry.
Also give the flap test real headroom -- it fitted 0.09s of sleeps into a
0.1s window and would have failed spuriously on a loaded runner.
Marc Billow
f12f67b2b3