[doc] Clarify the semi-deprecated ROS_REPOSITORY_PATH env var usage

[130s]

Found at #131 (comment)

I don't know if this is what we wanted/want. Thoughts?

If we decide to merge this change then we might want to inform users because this changes the default behavior.

[mathias-luedtke]

I would not merge it by now, but I think shadow should not be the default.
I really like the moveit_ci ROS_REPO variable, it would be great to have some shortcuts like shadow, shadow-fixed, stable, testing, building etc.

ROS_REPO and ROS_REPOSITORY_PATH won't be used with custom Docker images anyway (as the repo setup is part of the image).

We could implement the follwing logic:
If ROS_REPOSITORY_PATH is set, use it.
If not, try to derive it from ROS_REPO (which defaults to stable).

[130s]

I really like the moveit_ci ROS_REPO variable, it would be great to have some shortcuts like shadow, shadow-fixed, stable, testing, building etc.

You mean these moveit_ci. Indeed they look nice.

If ROS_REPOSITORY_PATH is set, use it.
If not, try to derive it from ROS_REPO (which defaults to stable).

+1

[mathias-luedtke]

Should we reissue this PR?

[mathias-luedtke]

Why did you replace ROS_REPOSITORY_PATH in the second commit?
This will fail!

[mathias-luedtke]

The new deafult can be set there

[130s]

Sorry, I was confused.

Added a bit more of the relationship of ROS_REPOSITORY_PATH and ROS_REPO to the document.

[130s]

Conflict resolved.

[mathias-luedtke]

Please don't set ROS_REPOSITORY_PATH as this will disable the ROS_REPO feature.
Default must be set there

[130s]

Please don't set ROS_REPOSITORY_PATH as this will disable the ROS_REPO feature.

I see, done (by simply resetting the commit that did wrong).
Title of the PR also updated now that this only changes a doc.

[mathias-luedtke]

Should I open another PR for the new default repo?