xflock4 gets stuck in unlock/lock cycle with some setups

I upgraded to Debian Trixie, and it looks like 42db188a changed the behaviour of the screen lock. Previously, multiple runs of xflock4 were asynchronous - if xflock4 were run when the screen was already locked, then the lock command would be executed immediately, and the screen would remain locked. Now, xflock appears to make a synchronous call, which blocks until complete, and any more runs while the screen is locked will also block, but then be executed after the original call unblocks. This results in an "unlock/lock" loop with setups using tools like xautolock:

xautolock -time 5 calls xflock4 every 5 minutes when there is no keyboard/mouse activity
so if screen is locked for an hour, xautolock will run xflock4 12 times
first xflock4 locks the screen
the next 11 runs block and can only lock the screen after the user unlocks it

This change may be deliberate, and if so, it's not hard to workaround, but it does break some existing setups so maybe it should be considered a bug if this change was unintentional (?).

To reproduce:

Run xautolock -time 1 -locker xflock4
Wait 5 minutes
Try to unlock
You will have to unlock several times

Run sleep 10 && xflock4 in a terminal
Run xflock4 in another terminal
You will need to unlock twice