persist override of HUGINN_PORT

[oskapt]

fixes #2447

[dsander]

Those legacy HUGINN_ prefixes keep biting us 😒

I think your solution should not break any other use case of the variables.

@baip Could you please double check that I am not missing something?

[baip]

I don't think it should affect anything else either. It's funny that I added the awk treatment specifically to handle Kubernetes where the container is named huginn but my later PR to clean up how .env is formed introduced this regression. My apologies!

[dsander]

@baip Thanks for double checking! There are simply too many possible configurations to remember all edge cases 😄 I added a test to the https://github.com/huginn/huginn_docker_specs repository.

@oskapt Thanks for the detailed description in the issue and the fix!