Build stuck on final "exit 0"

After executing successfully the shell script the workers remain stuck for 10 minutes on the final "exit 0".

There hasn't been any other failure that I could find: all the jobs run exactly as planned, they just don't seem to exit.

The fact that the jobs remain stuck for exactly 600 seconds makes me think of a timeout of some sort.

Reverting to 2.138 fixed the issue, that's why I am marking it as a regression.