After the recent update to mdadm v4.4 our test suite (libblockdev package) started failing when trying to remove a disk from existing RAID 1 array. This happens randomly and is probably a race condition as we try to remove the disk immediately after creating the array.

Steps to reproduce:
sudo mdadm --create --run test --level=raid1 --raid-devices=2 /dev/sda /dev/sdb
sudo mdadm --incremental --fail sda -v

The --incremental --fail command fails with:
mdadm: failed to write 'read-auto' to '/sys/block/md127/md//array_state' (Device or resource busy)
mdadm: Cannot remove member device sda from md127.