Allow custom user specified URL for upstream inside workspaces

Say I want to open a workspace for some GNOME module, let's use gnome-desktop. I do this:

$ cd gnome-build-meta
$ bst workspace open core/gnome-desktop.bst ~/Projects/gnome-desktop

Now I make some changes and want to push. I have to manually change the git repo's origin URL to use SSH:

git remote set-url origin ssh://mcatanzaro@git.gnome.org/git/gnome-desktop

It would be nice if I didn't have to do this manually. JHBuild allowed configuring a custom remote URL for different repositories, to handle this automatically. E.g. I have this in my jhbuildrc:

repos['git.gnome.org'] = 'ssh://mcatanzaro@git.gnome.org/git/'