Support providing custom branch name for build:env:push

[G-Rath]

Currently build:env:push is hard-coded to use the master branch if it's not a multi-dev call:

terminus-build-tools-plugin/src/Commands/BuildToolsBase.php

Line 804 in 2426c24

$branch = ($multidev == 'dev') ? 'master' : $multidev;

We've both moved to using main for our branches instead of master, and actually want to have a specific deployment branch that CI commits to so that devs don't have to do asset compiling themselves (e.g. we ignore our compiled assets, and then CI builds + forcefully commits them to the deployment branch, which is then deployed from).

I would say long-term it would probably make sense to make a global --default-branch config value that gets used in these situations.

[greg-1-anderson]

Right now, the build tools plugin assumes that the GitHub (/ GitLab / Bitbucket) branch always matches the Pantheon branch. The Pantheon branch for the dev environment must be "master". We've gotten a lot of requests to change this, but it's hardcoded in too many places to be changed easily, so it will be a while before this can be changed on the platform.

Build tools could, however, be modified to push from the default branch on GitHub (et. al.) to the master branch on Pantheon. This was discussed once; I don't recall what the challenges were.

[G-Rath]

Build tools could, however, be modified to push from the default branch on GitHub (et. al.) to the master branch on Pantheon.

Yeah that's what I had in mind - we're not fussed with what branch pantheon uses in the remote.

(tbh after doing more toying with this, I suspect I'm actually after a build:env:push-commit commit, but that can be another issue)