workflows/bot: allow maintainers to merge backports

All other conditions equal, there is no reason to prevent maintainers
from backporting changes to their packages. Maintainers are probably in
the *best* position to tell whether a certain change is backportable or
not - because they know the package well.

.github/workflows/backport.yml

@@ -57,8 +57,9 @@ jobs:
           pull_description: |-
             Bot-based backport to `${target_branch}`, triggered by a label in #${pull_number}.
 
-            * [ ] Before merging, ensure that this backport is [acceptable for the release](https://github.com/NixOS/nixpkgs/blob/master/CONTRIBUTING.md#changes-acceptable-for-releases).
+            **Before merging, ensure that this backport is [acceptable for the release](https://github.com/NixOS/nixpkgs/blob/master/CONTRIBUTING.md#changes-acceptable-for-releases).**
-              * Even as a non-committer, if you find that it is not acceptable, leave a comment.
+
+            Even as a non-committer, if you find that it is not acceptable, leave a comment.
 
       - name: Log current API rate limits
         env:

ci/README.md

@@ -42,10 +42,11 @@ These issues effectively list PRs the merge bot has interacted with.
 
 To ensure security and a focused utility, the bot adheres to specific limitations:
 
-- The PR targets `master`, `staging`, or `staging-next`.
+- The PR targets one of the [development branches](#branch-classification).
 - The PR only touches packages located under `pkgs/by-name/*`.
 - The PR is either:
-  - authored by a [committer][@NixOS/nixpkgs-committers], or
+  - authored by a [committer][@NixOS/nixpkgs-committers],
+  - backported via label, or
   - created by [@r-ryantm](https://nix-community.github.io/nixpkgs-update/r-ryantm/).
 - The user attempting to merge is a member of [@NixOS/nixpkgs-maintainers].
 - The user attempting to merge is a maintainer of all packages touched by the PR.

ci/github-script/merge.js

@@ -1,3 +1,5 @@
+const { classify } = require('../supportedBranches.js')
+
 function runChecklist({
   committers,
   files,
@@ -22,14 +24,14 @@ function runChecklist({
         .reduce((acc, cur) => acc?.intersection(cur) ?? cur)
 
   const checklist = {
-    'PR targets one of the allowed branches: master, staging, staging-next.': [
+    'PR targets a [development branch](https://github.com/NixOS/nixpkgs/blob/-/ci/README.md#branch-classification).':
-      'master',
+      classify(pull_request.base.ref).type.includes('development'),
-      'staging',
-      'staging-next',
-    ].includes(pull_request.base.ref),
     'PR touches only packages in `pkgs/by-name/`.': allByName,
     'PR is at least one of:': {
       'Authored by a committer.': committers.has(pull_request.user.id),
+      'Backported via label.':
+        pull_request.user.login === 'nixpkgs-ci[bot]' &&
+        pull_request.head.ref.startsWith('backport-'),
       'Created by r-ryantm.': pull_request.user.login === 'r-ryantm',
     },
   }