Don't generate a loader .py file in .egg file for extensions that aren't

actually built.  This prevents problems w/customized setups that make
some extensions optional (e.g. scipy.distutils).

--HG--
branch : setuptools
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/trunk/setuptools%4043201

setuptools/command/bdist_egg.py

@@ -307,7 +307,8 @@ class bdist_egg(Command):
                 fullname = build_cmd.get_ext_fullname(ext.name)
                 filename = build_cmd.get_ext_filename(fullname)
                 if not os.path.basename(filename).startswith('dl-'):
-                    ext_outputs.append(filename)
+                    if os.path.exists(os.path.join(self.bdist_dir,filename)):
+                        ext_outputs.append(filename)
 
         return all_outputs, ext_outputs
 
@@ -325,7 +326,6 @@ NATIVE_EXTENSIONS = dict.fromkeys('.dll .so .dylib .pyd'.split())
 
 
 
-
 def walk_egg(egg_dir):
     """Walk an unpacked egg's contents, skipping the metadata directory"""
     walker = os.walk(egg_dir)