use if main block in entry points

closes  #4698

setupbase.py

@@ -337,7 +337,8 b' def find_entry_points():'
 script_src = """#!{executable}
 # This script was automatically generated by setup.py
 from {mod} import {func}
-{func}()
+if __name__ == '__main__':
+    {func}()
 """
 
 class build_scripts_entrypt(build_scripts):