CI-02 probe D1: concurrency group kept, cancel-in-progress false, hold the slot

.gitea/workflows/checks.yml

@@ -1,15 +1,9 @@
-# CI-02 PROBE WORKFLOW - THROWAWAY. This branch is deleted after the run.
-#
-# It replaces the real gate with a set of one-bit steps, because this Gitea
-# 404s its Actions log endpoints and the ONLY machine-readable channel out of a
-# job is /api/v1/repos/.../actions/runs/<id>/jobs, which carries a per-STEP
-# conclusion. So each question this ticket has to answer is asked as its own
-# step, and the answer is read as that step's success or failure.
-#
-# There is deliberately NO `concurrency:` block: the point of pushes B and C is
-# to find out whether a still-WAITING run is cancelled by the next push even
-# when the workflow asks for no concurrency at all. If it is, the cancellation
-# is the server's and no edit to this file can prevent it.
+# CI-02 PROBE - THROWAWAY. Trial 2: CI-01's per-PR concurrency group kept, but
+# cancel-in-progress FLIPPED TO false. Trial 1 (no block at all) left a queued
+# run alive across two further pushes. This trial asks the narrower question the
+# fix actually turns on: does the group ALONE kill a queued run, the way GitHub
+# documents ("any previously pending job in the group will be cancelled"), or
+# was cancel-in-progress: true the whole cause?
 name: checks
 
 on:
@@ -17,6 +11,10 @@ on:
     branches: [release/1.0, master]
   workflow_dispatch:
 
+concurrency:
+  group: addon-checks-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: false
+
 jobs:
   unit:
     runs-on: [self-hosted, goodwe-rig]
@@ -24,62 +22,36 @@ jobs:
     env:
       WS: /home/homelab/ci/ci02probe-${{ github.run_number }}
       PRNUM: ${{ github.event.pull_request.number }}
-      PRHEAD: ${{ github.event.pull_request.head.sha }}
       BASEREF: ${{ github.base_ref }}
       TOKEN: ${{ secrets.GITHUB_TOKEN }}
       URL: ${{ github.server_url }}/${{ github.repository }}.git
     steps:
-      - name: P00 an empty clone to ask the server questions from
+      - name: Q00 an empty clone
         run: |
           set -eu
           rm -rf "$WS" && mkdir -p "$WS" && cd "$WS"
           git init -q .
           git remote add origin "$(echo "$URL" | sed "s#://#://x-access-token:${TOKEN}@#")"
-          echo "GITHUB_REF=$GITHUB_REF"
-          echo "GITHUB_SHA=$GITHUB_SHA"
-          echo "PRNUM=$PRNUM PRHEAD=$PRHEAD BASEREF=$BASEREF"
+          echo "BASEREF=[$BASEREF] PRNUM=[$PRNUM]"
 
-      - name: P01 GITHUB_REF is refs-pull-N-head (the bare head)
-        if: always()
-        run: |
-          set -eu
-          test "$GITHUB_REF" = "refs/pull/$PRNUM/head"
-
-      - name: P02 GITHUB_REF is refs-pull-N-merge (merged content)
-        if: always()
-        run: |
-          set -eu
-          test "$GITHUB_REF" = "refs/pull/$PRNUM/merge"
-
-      - name: P03 GITHUB_SHA equals the PR head sha
-        if: always()
-        run: |
-          set -eu
-          test "$GITHUB_SHA" = "$PRHEAD"
-
-      - name: P04 the first half of the shipped fallback fetches at all
+      - name: Q01 github.base_ref is populated and its branch fetches ALONE
         if: always()
         run: |
           set -eu
           cd "$WS"
-          git fetch -q --depth 1 origin "$GITHUB_REF"
+          test -n "$BASEREF"
+          git fetch -q origin "+refs/heads/$BASEREF:refs/remotes/origin/base"
+          git rev-parse refs/remotes/origin/base
 
-      - name: P05 ...and what it lands on IS the bare PR head
+      - name: Q02 the pull request head fetches ALONE
         if: always()
         run: |
           set -eu
           cd "$WS"
-          git fetch -q --depth 1 origin "$GITHUB_REF"
-          test "$(git rev-parse FETCH_HEAD)" = "$PRHEAD"
+          git fetch -q origin "+refs/pull/$PRNUM/head:refs/remotes/origin/pr"
+          git rev-parse refs/remotes/origin/pr
 
-      - name: P06 refs-pull-N-merge exists on the server for an OPEN pr
-        if: always()
-        run: |
-          set -eu
-          cd "$WS"
-          git fetch -q --depth 1 origin "refs/pull/$PRNUM/merge"
-
-      - name: P07 a real merge of this head into the base tip applies cleanly
+      - name: Q03 and only THEN does the merge itself refuse
         if: always()
         run: |
           set -eu
@@ -87,18 +59,12 @@ jobs:
           git fetch -q origin "+refs/heads/$BASEREF:refs/remotes/origin/base"
           git fetch -q origin "+refs/pull/$PRNUM/head:refs/remotes/origin/pr"
           git checkout -qf refs/remotes/origin/base
-          git -c user.email=ci@local -c user.name=ci merge --no-edit --no-ff refs/remotes/origin/pr
+          git -c user.email=ci@local -c user.name=ci merge --no-edit refs/remotes/origin/pr
 
-      - name: P08 the base tip is already an ancestor of the head
+      - name: Q09 hold the single runner slot
         if: always()
-        run: |
-          set -eu
-          cd "$WS"
-          git fetch -q origin "+refs/heads/$BASEREF:refs/remotes/origin/base"
-          git fetch -q origin "+refs/pull/$PRNUM/head:refs/remotes/origin/pr"
-          git merge-base --is-ancestor refs/remotes/origin/base refs/remotes/origin/pr
+        run: sleep 200
 
-      - name: P99 clean up
+      - name: Q99 clean up
         if: always()
         run: rm -rf "$WS" || true
-# probe C3 - a third push, to see whether the QUEUED run 561 survives it