Fix install model_config_pb2.py (#1538)

We are generating the model_config_pb2.py file from a protobuf script,
but doing this as part of the 'build_ext' phase - running at the same
time as building our native extensions. This caused the build to not
pick up the generated python file unless it already existed.

Fix by moving the proto generation to the correct 'build_py' phase

Author: benfred

setup.py

@@ -21,6 +21,8 @@
 from pybind11.setup_helpers import Pybind11Extension
 from pybind11.setup_helpers import build_ext as build_pybind11
 from setuptools import find_namespace_packages, find_packages, setup
+from setuptools.command.build_py import build_py as _build_py
+from setuptools.command.develop import develop as _develop
 
 try:
     import versioneer
@@ -33,9 +35,8 @@
     import versioneer
 
 
-class build_pybind_and_proto(build_pybind11):
+class build_proto(_build_py):
     def run(self):
-        build_pybind11.run(self)
         protoc = None
         if "PROTOC" in os.environ and os.path.exists(os.environ["PROTOC"]):
             protoc = os.environ["PROTOC"]
@@ -61,6 +62,16 @@ def run(self):
             else:
                 print("not regenerating", output, " - file exists and proto hasn't been updated")
 
+        super().run()
+
+
+class develop(_develop):
+    def run(self):
+        # running setup.py develop doesn't seem to run 'build_py' force this to run
+        # so we get our proto files installed
+        self.run_command("build_py")
+        super().run()
+
 
 ext_modules = [
     Pybind11Extension(
@@ -78,7 +89,9 @@ def run(self):
 
 
 cmdclass = versioneer.get_cmdclass()
-cmdclass["build_ext"] = build_pybind_and_proto
+cmdclass["build_ext"] = build_pybind11
+cmdclass["build_py"] = build_proto
+cmdclass["develop"] = develop
 
 
 def parse_requirements(filename):