simplified pipeline to ensure it works with PRs

Author: jamesdbloom

.buildkite/pipeline.yml

@@ -5,4 +5,4 @@ steps:
   - wait
 
   - label: "build"
-    command: "docker run -v /var/lib/buildkite-agent/builds/$BUILDKITE_AGENT_NAME/mockserver:/build -w /build/mockserver-ui -a stdout -a stderr mockserver/mockserver:grunt /build/mockserver-ui/scripts/local_quick_build.sh"
+    command: "docker run -v $(pwd):/build/mockserver-ui -w /build/mockserver-ui -a stdout -a stderr -e BUILDKITE_BRANCH=$BUILDKITE_BRANCH mockserver/mockserver:grunt /build/mockserver-ui/scripts/local_quick_build.sh"