Hello, A nice feature would be to be able to use a pull-request as branch to specify in the `--with-branch` transformation option. A use-case is to use a pull-request coming from a private fork, thus we can't use the combination `--with-git-url= with-branch=`. As an example, if I follow https://gitlab.inria.fr/help/user/project/merge_requests/reviews/index.md#checkout-merge-requests-locally-through-the-head-ref, I should be able to do something like: ```bash guix build chameleon --with-branch=chameleon=merge-requests/262/head ``` (with 262 being the pull-request I'm interested in) However, this fails: ``` guix build: erreur : impossible de récupérer la branche « merge-requests/262/head » depuis https://gitlab.inria.fr/solverstack/chameleon : cannot locate remote-tracking branch 'origin/merge-requests/262/head' ``` While commands stated in the documentation work well: ```bash git clone https://gitlab.inria.fr/solverstack/chameleon && cd chameleon git fetch origin merge-requests/262/head:mr-262 git checkout mr-262 ``` I guess the fetch step is lacking in the way Guix handles the `--with-branch` transformation. FYI, Ansible is able to do things like that (see https://docs.ansible.com/ansible/latest/collections/ansible/builtin/git_module.html), by combining options `refspec` and `version`. I'm aware a workaround is to download the patch corresponding to the pull-request and using `--with-patch`, however handling it directly with `--with-branch` would be more handy ! Thanks, -- Philippe SWARTVAGHER PhD Student TADaaM team, Inria Bordeaux Sud-Ouest