My part is: ``` parts: ros2-galactic-extension: build-packages: [ros-galactic-ros-core] override-build: install -D -m 0755 launch ${SNAPCRAFT_PART_INSTALL}/snap/command-chain/ros2-launch plugin: nil source: $SNAPCRAFT_EXTENSIONS_DIR/ros2 ``` It uses source from snapcraft. This works fine locally but When I try remote-build, I get: ``` Failed to pull source: unable to determine source type of '$SNAPCRAFT_EXTENSIONS_DIR/ros2'. Check that the URL is correct, or consider specifying `source-type` for this part. See `snapcraft help sources` for more information. ``` I couldn't find `source-type` that would work for my case.