ci: fix PR rebasing

Author: Splaktar

.circleci/config.yml

@@ -58,6 +58,14 @@ commands:
     description: Checkout and verify clean merge with master
     steps:
       - checkout
+      - run:
+          name: Configure Git for rebase
+          command: |
+            if [ -n "$CIRCLE_PR_NUMBER" ]; then
+            # User is required for rebase.
+            git config user.name "angular-ci"
+            git config user.email "angular-ci"
+            fi
       - build-tools/merge-with-parent:
           parent: master