Processors updates break execution

[kr1zz]

Let's consider application A that launches one or more instances of application B. We need to update application B

Scenario 0:

1. application A is started but hasn't reached the point where B is executed
2. application B is updated
3. while the update is ongoing or right after it is done, application B is executed by A

Scenario 1:

1. application A executed several instances of B, which get queued
2. application B is updated

In at least one of these scenarios, application B starts but fails with the usual message of newly updated applications (please wait, or contact email, or ask on Discord...)

We should:

1. ASAP: prevent the problem from happening (maybe keep the queued instances of application B from running until the update is executed)
2. later: maybe manage versions, so that if B is at version n, and is expected to become version n+1, then every instance launched by a process started earlier than the time at which B is updated will keep launching version n, whereas newer processes that are started after the time of update of B use version n+1