Fetch all branches and tags to support git tests, and explicitly checkout master branch so that it is available in the local repo

Author: bbpennel

.github/workflows/build.yml

@@ -11,6 +11,12 @@ jobs:
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - run: |
+            git fetch origin master
+            git checkout -b master
+            git checkout ${{ github.event.pull_request.head.sha }}
     - name: Set up JDK 1.8
       uses: actions/setup-java@v1
       with: