Duplicate runs using default cache lock

[dom-devel]

What's the issue

We're having some issues where two crons end up running at the same time.

We're using the cache lock (i.e. default) and version: ==0.5.1

It seems like there was an update to the FILE_LOCK cache Simplifies the file-based lock mechanism and fixes the race condition, but none as far as I could see to the cache lock.

Is this a known issue?

Details
We've got a cron job which runs every 10 minutes.

RUN_EVERY_MINS = 10
schedule = Schedule(run_every_mins=RUN_EVERY_MINS)

Which is then called by our cron runner every 10 minutes.

*/10 * * * *

This seems to work out at the cron running about 3-4 times an hour. I'd guess there is some sort of time mismatch?

This wouldn't be the end of the world, except occasionally it does this and triggers the cron twice approximately 1 minute apart:

And when this happens, it seems that the cron seems to run simultaneously despite not having parallel runs enabled.