It's not possible to run multiple tasks at the same time locally

[Kipok]

Since all of our containers expose ports and share host network, we cannot e.g. host multiple servers or sandboxes or in general run any pipeline tasks in parallel. Ideally we should fix this, but it might require engineering some way to pass in task-specific network between containers instead of using the host

[Kipok]

At least we should ideally raise a clear error message as it's a bit hard to debug the first time you see it.