Scenario: clone-from-submodule, with a branch

The submodule names branch = stable in .gitmodules: the branch git submodule update --remote follows. The splice follows it too: .splice records it as the upstream's default-branch (default-branch).

Monorepo, on main: vendor/a/ is a submodule of the upstream, checked out at seed, with branch = stable.
Upstream ($UPSTREAM, reached as https://git.example.com/a.git): seed, then newer on main, and stable fix on stable.

Output

setup.bash builds this state:

$ build_scenario scenario_submodule_with_branch https://git.example.com/a.git

$ cat .gitmodules
[submodule "vendor/a"]
	path = vendor/a
	url = https://git.example.com/a.git
	branch = stable

$ git splice clone --from-submodule vendor/a
===  vendor/a: fetching https://git.example.com/a.git
ok   vendor/a: cloned bde4164 from the submodule
===  vendor/a: the submodule's repository stays in .*/monorepo/\.git/modules/vendor/a -- remove it once you don't need it (regex)

$ cat vendor/a/.splice
[splice]
	id = 9ec04ba433cffaa4
	commit = bde416459fbcc09c9b585f3b65a94cab3f68bfcd
[upstream "origin"]
	url = https://git.example.com/a.git
	default-branch = stable

main syncs with stable, so stable fix is there to pull, and newer isn't:

$ git splice status
On branch main

  behind 1  vendor/a -> stable

Output​

Output