Comment 6 for bug 48971

We already have an abstraction at the Transport layer.
My recommendation would be to write a GnomeTransport (or possibly VFSTransport), which would then register all names starting with either gnome+ or vfs+

Then you could access branches as:

vfs+sftp://host/foo/bar
vfs+smb://host/share

Or whatever the gnome notation is. All you need is a custom prefix (foo+ works well), and then register your custom Transport as a handler for those paths.
Then bazaar will happily use your transport for any of those urls.