Git URL scheme handling: whitelist path instead of non-path protocols

At some point we have to decide if a given git repository URL is
a path. So far, we assumed that anything not starting with ssh://,
http://, or https:// is a path. This ignores the facts that
- the file:// scheme, while referring to a file, does not denote
  a relative path starting file://,
- the [user@]host:path scheme is not a path on the local machine,
- there exist the URL schemes git://, ftp://, and ftps://, and
- future extension might add additional schemes.

To also correctly handle new schemes that git might add (which we
indeed can handle, as we simply shell out to the git binary), we
reverse the approach: we give the user the means to unambigiously
specify that they refer to a path on the local machine, by either
- using the file:// scheme,
- providing an absolute path starting with /, or
- providing a relative path starting with ./

All other schemes will not be modified. The file scheme, as well
as the git://, http://, and https:// scheme, are handled interally
using libgit2; all others are passed on to git in an unmodified form.

0 files changed, 0 insertions, 0 deletions