Don't recurse into subdirectories when scanning --find-links

--HG--
branch : setuptools
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/trunk/setuptools%4042822

setuptools/package_index.py

@@ -182,7 +182,7 @@ class PackageIndex(Environment):
             self.warn("Not found: %s", url)
             return
 
-        if os.path.isdir(fn):
+        if os.path.isdir(fn) and not nested:
             path = os.path.realpath(fn)
             for item in os.listdir(path):
                 self.process_filename(os.path.join(path,item), True)