Follow-up from "Automatically retarget merge requests [RUN ALL RSPEC] [RUN AS-IF-FOSS]"
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The following discussions from !53710 should be addressed:
- [ ] @ayufan started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/53710#note_505827321): (+7 comments)
> Fix `Delete Source Branch` when clicked manually by user
- [x] @pedroms started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/53710#note_509349705): (+1 comment)
> @ayufan 📝 **Text**: thank you for adding this separate message for automatic retargeting :bow: I have a few notes for your appreciation:
>
> 1. Per https://gitlab.com/gitlab-org/gitlab/-/merge_requests/53710#note_507810614, it would be ideal to communicate that `old_branch` was deleted in another merge request so that the `new_branch` selection makes just _a little bit_ more sense. As a developer that just stumbled upon this new kind of system note, would the following make more sense to you?
> 1. `Name (@username) automatically changed #{branch_type} branch to `#{new_branch}` because `#{old_branch}` was deleted in another merge request`
> 1. Consider moving `automatically` so the sentence reads a bit better: “[+automatically+] changed [-automatically-] target branch…”
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