Jenkins: Build image inside empty directoy

tests/modules/Jenkinsfile

@@ -3,6 +3,7 @@
 def prepareDocker () {
     def img
     stage('Prepare environment') {
+        dir('.imagebuild') {
             def uid = sh returnStdout: true, script: 'id -u'
             writeFile file: 'Dockerfile', text: """
             FROM python:3.8-buster
@@ -11,6 +12,7 @@ def prepareDocker () {
             """
             img = docker.build('local:test-all-comics')
         }
+    }
     return img
 }