I don't think there was any documentation for the _old_ behavior, and
certainly jk/submodule-c-credential didn't add any. But it probably is
worth document, maybe as part of "-c"? Care to roll a patch on top?
Sure.
I think we'd actually do it all in one, and that patch looks something
like the one below (on top of jk/submodule-config-sanitize-fix).
$ git checkout origin/jk/submodule-config-sanitize-fix
$ git am p
Applying: submodule: stop sanitizing config options
error: patch failed: builtin/submodule--helper.c:246
error: builtin/submodule--helper.c: patch does not apply
error: patch failed: submodule.c:1131
error: submodule.c: patch does not apply
Patch failed at 0001 submodule: stop sanitizing config options
So if you want some documentation on top of that, where would I base it on?