N.B. there's a sibling [`check-queued-merge-requests.py` script](https://gitlab.freedesktop.org/freedesktop/snippets/-/snippets/7783) that allows MRs to be labelled as `Merge now` or `Merge in 8h` or `Merge in 7 days` etc. and that checks from time to time if enough time has expired on those MRs and then assigns them to Marge. The problem described in the code comment relates to the fact that MR pipelines (in GStreamer) start automatically when the MR is assigned to Marge but are behind a manual trigger otherwise to save CI resources. So we don't want to assign backport MRs directly to Marge in GStreamer because then CI might be running for multiple backport MRs, wasting CI resources. We solve that by adding the `Merge now` label to backport MRs via the `--labels='Merge now'` command line option to the script, and then the other script above will go and assign the MR to Marge next time it checks (which will be after the MR pipeline has been created and will be waiting for a manual trigger), and when Marge gets around to it she will rebase the MR to add `Part-of:` footers with the links to the backport MR, and then the pipeline will start when the rebased/amended branch gets pushed.