The write-heavy test innodb_zip.wl6501_scale_1 timed out on
10.2 60d7011c for me.
Out of os_aio_n_segments=6, 5 are waiting for an event in
os_aio_simulated_handler(). One thread is waiting for a
write to complete in buf_dblwr_add_to_batch(), but that
would never happen, because nothing is waking up the simulated AIO
handler threads.

This hang appears to have been introduced in MySQL 5.6.12
in mysql/mysql-server@26cfde776cdf5ce61bd5cc494dfc1df28c76977f.