Fix escaping in groovy

Author: jc21

Jenkinsfile

@@ -73,7 +73,7 @@ pipeline {
 				script {
 					def shStatusCode = sh(label: 'build-frontend', returnStatus: true, script: '''
 						set -e
-						./scripts/ci/build-frontend | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g" > ${WORKSPACE}/tmp-sh-build 2>&1
+						./scripts/ci/build-frontend | sed -r "s/\\x1B\\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g" > ${WORKSPACE}/tmp-sh-build 2>&1
 					''')
 					shOutput = readFile "${env.WORKSPACE}/tmp-sh-build"
 					if (shStatusCode != 0) {