sage_setup.sage_setup: Do not expand packages to modules

Author: Matthias Koeppe

src/sage_setup/__init__.py

@@ -30,6 +30,7 @@ def sage_setup(distributions, *,
     from distutils import log
     from setuptools.dist import Distribution
     from sage_setup.command.sage_build_ext_minimal import sage_build_ext_minimal
+    from sage_setup.command.sage_build_py import sage_build_py
     from sage_setup.cython_options import compiler_directives, compile_time_env_variables
     from sage_setup.extensions import create_extension
     from sage_setup.find import find_python_sources, find_extra_files
@@ -69,7 +70,8 @@ def sage_setup(distributions, *,
     sage.env.default_required_modules = required_modules
     sage.env.default_optional_modules = optional_modules
 
-    cmdclass = dict(build_ext=sage_build_ext_minimal)
+    cmdclass = dict(build_ext=sage_build_ext_minimal,
+                    build_py=sage_build_py)
 
     sdist = len(sys.argv) > 1 and (sys.argv[1] in ["sdist", "egg_info", "dist_info"])
 

src/sage_setup/command/sage_build_py.py

@@ -0,0 +1,12 @@
+from setuptools.command.build_py import build_py
+
+
+class sage_build_py(build_py):
+
+    def find_package_modules(self, package, package_dir):
+        r"""
+        Do not expand packages to modules.
+
+        Our :func:`sage_setup.find.find_python_sources` already lists all modules.
+        """
+        return []