bazel build error: 'xxx' does not appear in srcs

用bazel编译时，BUILD文件是这样写的:

但编译时，提示此BUILD文件有如下报错：
BUILD:8:10: in srcs attribute of py_binary rule //scripts:vehicle_config_downloader_py: corresponding default 'vehicle_config_downloader_py.py' does not appear in srcs. Add it or override default file name with a 'main' attribute

解决方法：