fix(release): checkout branch and avoid being in a detached HEAD

Jenkinsfile

@@ -5,16 +5,20 @@ def org = 'fabric8-ui'
 def repo = 'ngx-base'
 fabric8UINode{
   ws {
-    git "https://github.com/${org}/${repo}.git"
+    checkout scm
+
     readTrusted 'release.groovy'
-    sh "git remote set-url origin [email protected]:${org}/${repo}.git"
+
     def pipeline = load 'release.groovy'
 
     if (utils.isCI()){
       container('ui'){
         pipeline.ci()
       }
     } else if (utils.isCD()){
+      sh "git checkout master"
+      sh "git remote set-url origin [email protected]:${org}/${repo}.git"
+
       def branch
       container('ui'){
           branch = utils.getBranch()