cpkg: set git identity before merge

vars/cpkg.groovy

@@ -31,11 +31,14 @@ def call(Map params = [:]) {
 
         // Merge currentRef into distBranch and push
         sh("git checkout -b '${distBranch}' 'origin/${distBranch}'")
+
+        // Add git username/email
+        sh("git config user.email '${gitEmail}'")
+        sh("git config user.username '${gitUsername}'")
+
         sh("git merge ${currentRef}")
 
         if (!skipPush) {
-            sh("git config user.email '${gitEmail}'")
-            sh("git config user.username '${gitUsername}'")
             sh("git push")
         } else {
             println("Skipping push. Set skipPush param to 'true' to enable remote repository update.")