Cloning doesn't work with relative path in .gitmodules

[Kinokin]

Using relative pathes in .gitmodules like

[submodule "external/7z"]
path = external/7z
url = ../../external/7z.git

fails:
$ python3.8 ../git-partial-submodule.py clone
fatal: repository '../../external/7z.git' does not exist
Git command failed: git clone --filter=blob:none --no-checkout --separate-git-dir /tmp/nena/.git/modules/external/7z ../../external/7z.git /tmp/nena/external/7z

Looks like in case of a relative url the path to main project needs to be added