Fix no such directory error on CI

See gh-20530

ci/scripts/create-pull-request.sh

@@ -1,9 +1,7 @@
 #!/bin/bash
 set -e
 
-commit_message=$( cat commit-details/message )
-
-if [[ ${commit_message} != "" ]]; then
+if [[ -f commit-details/message ]]; then
 	curl \
 	  -s \
 		-u ${GITHUB_USERNAME}:${GITHUB_PASSWORD} \

ci/scripts/detect-docker-updates.sh

@@ -28,6 +28,7 @@ if [[ ${existing_upgrade_issues} = "" ]]; then
 	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."