Cancel superseded pull request runs

A new commit on a pull request makes the previous run's result
irrelevant, but the runners keep going: pushing three commits in quick
succession earlier today left nine Spack legs building a superseded
commit for close to two hours.

Add a concurrency group to the seven workflows that run on
'pull_request'. Cancellation is limited to that event, so pushes to
'main' and 'release' still finish -- the Spack workflow populates the
build cache from them, and a cancelled run skips those push steps.

Merge queue runs are unaffected: they carry a
'refs/heads/gh-readonly-queue/...' ref, so they form their own group, and
'cancel-in-progress' is false for anything that is not a pull request.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: garth-wells

.github/workflows/ccpp.yml

@@ -15,6 +15,13 @@ on:
       - main
   workflow_dispatch:
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
 
   lint:

.github/workflows/ci-spack.yml

@@ -14,6 +14,13 @@ on:
       - main
   workflow_dispatch:
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 env:
   GITHUB_USER: ${{ github.actor }}
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/ci.yml

@@ -10,6 +10,13 @@ on:
       - main
   workflow_dispatch:
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 env:
   GITHUB_USER: ${{ github.actor }}
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/conda.yml

@@ -16,6 +16,13 @@ on:
     - cron: "0 2 * * WED"
   workflow_dispatch: ~
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 env:
   UCX_TLS: tcp  # Use TCP only, avoiding InfiniBand/MANA
 

.github/workflows/macos.yml

@@ -15,6 +15,13 @@ on:
       - main
   workflow_dispatch:
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
 
   mac-os-build:

.github/workflows/sonarcloud.yml

@@ -12,6 +12,13 @@ on:
   workflow_dispatch:
 
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
   sonarcloud-build:
     name: Build

.github/workflows/windows.yml

@@ -12,6 +12,13 @@ on:
       - main
   workflow_dispatch:
 
+# Cancel superseded runs: a new commit on a pull request makes the
+# previous run's result irrelevant. Pushes to 'main' and 'release' are
+# left to finish, since they populate caches and publish artefacts.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
 
   windows-build: