helpers: Decide LMP_VERSION by branch instead of HEAD

[angolini]

Instead of always searching for the latest tag from main, first detect which branch was initialized by repo and then fetch the latest tag.

Tested by

repo init --no-clone-bundle -u https://github.com/foundriesio/lmp-manifest -b main
export H_PROJECT=lmp
source /home/daiane/foundries/ci-scripts/helpers.sh 
set_base_lmp_version


repo init --no-clone-bundle -u https://github.com/foundriesio/lmp-manifest -b scarthgap
export H_PROJECT=lmp
source /home/daiane/foundries/ci-scripts/helpers.sh 
set_base_lmp_version

I'm not exactly sure how to get the first repo init command line, so I guessed. If there is a better way to test it, please advice.

It returns 96 for main and 97 for scarthgap, as the main logic of using the next version is maintained

[ricardosalveti]

But then main will use the v96 + 1 bucket, is this what we want?

[ricardosalveti]

If we don't expect releasing main anymore I would just move main to use a different sstate cache bucket and drop most of this logic.

[angolini]

@ricardosalveti I'm still unsure how to proceed, in an attempt of better understanding this I made this silly change.

Not exactly thinking about tags on main, but tags on each LTS branch, how to keep it up with CVE stable updates being released in the future.

I agree that the sstate_cache remote directories management has to align with this logic. But today this management is unclear to me, so I hear any feedback.