Add a lockable resource named "test_res"

Add a pipeline job with only this code:

node {

lock('test_res') {
echo 'locked'
}
echo 'unlocked'
}

Run this job. It should work fine.

Now perform a manual reserve of the resource via the lockable resource interface.
Start the job again.
It correctly waits for the resource:
[Pipeline] node {
[Pipeline] Lock shared resource : Start
Trying to acquire lock on [test_res]
[test_res] is locked, waiting...

Now go back to the Lockable Resource user interface.
Manually unlock the resource.

Expected result: the locked job should retry the lock, see that it has been freed, continue (locking the resource and freeing it) and finish correctly.

Observed result: after waiting for > 5 minutes, nothing changed. The job stayed in exactly the same situation (output as above) and had to be cancelled.