Fix case when pull request already exists

If a PR with the given title exists, we clone the existing PR branch so
that it doesn't get overridden by master.

See gh-20530

ci/pipeline.yml

@@ -189,6 +189,7 @@ jobs:
 - name: detect-docker-updates
   plan:
   - get: git-repo
+  - get: git-repo-ci-docker
   - get: every-wednesday
     trigger: true
   - get: spring-boot-ci-image

ci/scripts/create-pull-request.sh

@@ -11,5 +11,5 @@ if [[ -f commit-details/message ]]; then
 		-X \
 		POST "https://api.github.com/repos/${GITHUB_ORGANIZATION}/${GITHUB_REPO}/pulls" > /dev/null || { echo "Failed to create pull request" >&2; exit 1; }
 else
-	echo "Already up-to-date"
+	echo "Already up-to-date."
 fi

ci/scripts/detect-docker-updates.sh

@@ -1,5 +1,16 @@
 #!/bin/bash
 
+existing_tasks=$( curl -s https://api.github.com/repos/${GITHUB_ORGANIZATION}/${GITHUB_REPO}/pulls\?labels\=type:%20task\&state\=open\&creator\=spring-buildmaster )
+existing_upgrade_issues=$( echo "$existing_tasks" | jq -c --arg TITLE "$ISSUE_TITLE" '.[] | select(.title==$TITLE)' )
+
+if [[ ${existing_upgrade_issues} = "" ]]; then
+  git clone git-repo git-repo-updated > /dev/null
+else
+  git clone git-repo-ci-docker git-repo-updated > /dev/null
+  echo "Pull request already exists."
+  exit 0
+fi
+
 latest_version=$(curl -I -s https://github.com/docker/docker-ce/releases/latest | grep "location:" | awk '{n=split($0, parts, "/"); print substr(parts[n],2);}' | awk '{$1=$1;print}' | tr -d '\r' | tr -d '\n' )
 
 if [[ $latest_version =~ (beta|rc) ]]; then
@@ -15,21 +26,12 @@ if [[ $current = $latest ]]; then
 	exit 0;
 fi
 
-existing_tasks=$( curl -s https://api.github.com/repos/${GITHUB_ORGANIZATION}/${GITHUB_REPO}/pulls\?labels\=type:%20task\&state\=open\&creator\=spring-buildmaster )
-existing_upgrade_issues=$( echo "$existing_tasks" | jq -c --arg TITLE "$ISSUE_TITLE" '.[] | select(.title==$TITLE)' )
-
-git clone git-repo git-repo-updated > /dev/null
-
-if [[ ${existing_upgrade_issues} = "" ]]; then
-	pushd git-repo-updated > /dev/null
-	git config user.name "Spring Buildmaster" > /dev/null
-	git config user.email "buildmaster@springframework.org" > /dev/null
-	sed -i "s/version=.*/version=\"$latest_version\"/" ci/images/get-docker-url.sh
-	git add ci/images/get-docker-url.sh > /dev/null
-	commit_message="Upgrade to Docker $latest_version in CI"
-	git commit -m "$commit_message" > /dev/null
-	popd
-	echo ${commit_message} > commit-details/message
-else
-	echo "Pull request already exists."
-fi
+pushd git-repo-updated > /dev/null
+git config user.name "Spring Buildmaster" > /dev/null
+git config user.email "buildmaster@springframework.org" > /dev/null
+sed -i "s/version=.*/version=\"$latest_version\"/" ci/images/get-docker-url.sh
+git add ci/images/get-docker-url.sh > /dev/null
+commit_message="Upgrade to Docker $latest_version in CI"
+git commit -m "$commit_message" > /dev/null
+popd
+echo ${commit_message} > commit-details/message

ci/tasks/detect-docker-updates.yml

@@ -2,6 +2,7 @@
 platform: linux
 inputs:
   - name: git-repo
+  - name: git-repo-ci-docker
 outputs:
   - name: git-repo-updated
   - name: commit-details