Since git 2.38.1, cloning from local file is disabled by default for security issue. This makes tests fail. So set 'protocol.file.allow=always' for avoiding this issue.
And move 'git_submodule_add' utility function to 't/Util.t' because it is used only from test code.
Since git 2.38.1, cloning from local file is disabled by default for security issue. This makes tests fail. So set 'protocol.file.allow=always' for avoiding this issue.
And move 'git_submodule_add' utility function to 't/Util.t' because it is used only from test code.
Reference