Function check_submodule_url 

pub fn check_submodule_url(url: &str) -> bool

Port of check_submodule_url (git submodule-config.c). Returns true if the URL is acceptable (per the CVE-2020-11008 / option-injection checks), false otherwise (git’s 0 vs -1). Mirrors the relative-URL and git:// newline/../-escape checks; the http(s) url_normalize round-trip is approximated by the same newline check on the decoded form (sley has no url_normalize yet — TODO(submodule) below).