[cherry-pick] Add workflow to cherry pick commits to master (#37)

.github/workflows/cherry-pick.yml

@@ -0,0 +1,30 @@
+name: cherry-pick
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v1
+
+      - name: Prepare git
+        run: |
+          git config --global user.name "1gtm"
+          git config --global user.email "[email protected]"
+
+      - name: Install GitHub CLI
+        run: |
+          curl -fsSL https://github.com/github/hub/raw/master/script/get | bash -s 2.14.1
+          sudo mv bin/hub /usr/local/bin
+
+      - name: Update release branches
+        env:
+          GITHUB_USER: 1gtm
+          GITHUB_TOKEN: ${{ secrets.LGTM_GITHUB_TOKEN }}
+        run: |
+          ./hack/scripts/cherry-pick.sh

hack/scripts/cherry-pick.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+# Copyright The Stash Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -eou pipefail
+
+should_cherry_pick() {
+    while IFS=$': \t' read -r -u9 marker v; do
+        if [ "$marker" = "/cherry-pick" ]; then
+            return 0
+        fi
+    done 9< <(git show -s --format=%b)
+    return 1
+}
+
+should_cherry_pick || {
+    echo "Skipped cherry picking."
+    echo "To automatically cherry pick, add /cherry-pick to commit message body."
+    exit 0
+}
+
+git remote set-url origin https://${GITHUB_USER}:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git
+
+while IFS=/ read -r -u9 repo branch; do
+    git checkout $branch
+    pr_branch="master-${GITHUB_SHA:0:8}"${branch#"release"}
+    git checkout -b $pr_branch
+    git cherry-pick --strategy=recursive -X theirs $GITHUB_SHA
+    git push -u origin HEAD -f
+    hub pull-request \
+        --base $branch \
+        --labels automerge \
+        --message "[cherry-pick] $(git show -s --format=%s)" \
+        --message "$(git show -s --format=%b)" || true
+    sleep 2
+done 9< <(git branch -r | grep release)