DroneCI doesn't fetch tags by default

- Added `git fetch --tags` as the first command
- Changes to compile_vergen.sh in order to debug.

.drone.yml

@@ -20,6 +20,7 @@ steps:
     depends_on:
       - build-image
     commands:
+      - git fetch --tags
       - find . -type f -print0 | xargs -0 dos2unix
       - chmod +x /drone/src/*.sh
       - /drone/src/compile.sh