From 629dd15350e894c124b1b43d1c569e1e7d8d7728 Mon Sep 17 00:00:00 2001
From: Ben Barham <ben_barham@apple.com>
Date: Tue, 2 Dec 2025 09:15:27 +1000
Subject: [PATCH] Update automerge.yml when new release branches are created

---
 .github/workflows/auto_update_version.yml | 27 ++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/auto_update_version.yml b/.github/workflows/auto_update_version.yml
index 2577047a..bd3f013d 100644
--- a/.github/workflows/auto_update_version.yml
+++ b/.github/workflows/auto_update_version.yml
@@ -44,21 +44,38 @@ jobs:
           git checkout -b $UPDATE_BRANCH $RELEASE_BRANCH
 
       - name: Update PrintVersion.swift
-        id: update_version
         run: |
           FILE=Sources/swift-format/PrintVersion.swift
 
           if grep -q "print(\"$VERSION\")" "$FILE"; then
             echo "Version already $VERSION; skipping update."
-            echo "changed=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi
 
           sed -i "s/print(\".*\")/print(\"$VERSION\")/" "$FILE"
-          echo "changed=true" >> "$GITHUB_OUTPUT"
+
+      - name: Update automerge.yml
+        run: |
+          FILE=.github/workflows/automerge.yml
+
+          if grep -q "base_branch: $RELEASE_BRANCH" "$FILE"; then
+            echo "Branch already $RELEASE_BRANCH; skipping update."
+            exit 0
+          fi
+
+          sed -i "s/base_branch: .*/base_branch: $RELEASE_BRANCH/" "$FILE"
+
+      - name: Checking for changes
+        id: change_check
+        run: |
+          if git diff --exit-code; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
 
       - name: Commit and push changes
-        if: steps.update_version.outputs.changed == 'true'
+        if: steps.change_check.outputs.changed == 'true'
         run: |
           git config user.name "swift-ci"
           git config user.email "swift-ci@users.noreply.github.com"
@@ -67,7 +84,7 @@ jobs:
           git push origin $UPDATE_BRANCH
 
       - name: Create Pull Request
-        if: steps.update_version.outputs.changed == 'true'
+        if: steps.change_check.outputs.changed == 'true'
         env:
           GH_TOKEN: ${{ github.token }}
         run: |