T2: both children hold their first locks; gate opened
T2_RESULT: BUG-REPRODUCED both processes still blocked in F_SETLKW after 4s; POSIX requires EDEADLK for the cycle closer (sleep is PCATCH: killable)
child2[967]: F_SETLKW(A) -> rc=0 errno=0 (ok)
T2: children reaped, guest clean
EXIT=0