Extension installs in Dockerfile.dev overridden

[MikiDi]

Hi,

While setting up a development environment using docker-compose.dev.yml, I noticed that extensions installed through pip in Dockerfile.dev won't be taken into account, because of

ckan-docker/docker-compose.dev.yml

Line 32 in fc90a89

- home_dir:/srv/app/

I found this to be confusing. Is this intentional? Just removing the home_dir mounted volume solves the problem for me.
What is the correct way to run a CKAN Docker development setup that combines both extensions installed through the Dockerfile and an extension in development with local sources under src?

Thx!