Scenario: clone-from-submodule, with `branch = .`

The submodule names branch = . in .gitmodules: it follows the upstream branch named like the monorepo's current one. A splice does that already, so .splice records neither default-branch nor default-pin.

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

Output

setup.bash builds this state:

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

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

$ 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 = 680c4d19f10b5b95
	commit = bde416459fbcc09c9b585f3b65a94cab3f68bfcd
[upstream "origin"]
	url = https://git.example.com/a.git

main syncs with the upstream's main, so newer is there to pull:

$ git splice status
On branch main

  behind 1  vendor/a

Output​

Output