Issue with markers in isolation tester? Or not?

Hello, everyone!

While stabilizing tests for [0] I have noticed unclear (and confusing in my
opinion) behavior of markers in the isolation tester.

I have attached a test with reproducer.

There are two permutations in the test:

permutation
after(before)
before
detach1
wakeup1
detach2
wakeup2

In that case, I see expected results:
step before: <... completed>
step after: <... completed>

But changing the order of steps slightly:

permutation
after(before)
wakeup1 <------- wakeup moved here
before
detach1
detach2
wakeup2

makes "after" to be completed before "before". Does that make sense?

In my cases, there are 2-steps of injection points for each of 3 sessions,
so, it is difficult to make it bullet-proof in that case without a lot of
additional injection points.

Best regards,
Mikhail.

[0]:
https://www.postgresql.org/message-id/flat/ZnoZ6GNwkJmq-gTh%40paquier.xyz#4d13f826fb1e62860cc3ae30067bd23a