src/setup.py: Restrict cythonize to sage/**

Author: Matthias Koeppe

src/setup.py

@@ -106,7 +106,7 @@
         from Cython.Build import cythonize
         from sage.env import cython_aliases, sage_include_directories
         extensions = cythonize(
-            ["**/*.pyx"],
+            ["sage/**/*.pyx"],
             exclude=files_to_exclude,
             include_path=sage_include_directories(use_sources=True) + ['.'],
             compile_time_env=compile_time_env_variables(),