Good pratice when you have to write data in a binary file.

src/zc/buildout/networkcache.py

@@ -91,6 +91,7 @@ def download_network_cached(sha_dir, sha_cache, path, url, logger, md5sum=None):
 
         f = open(path, 'w+b')
         try:
+          f.seek(0)
           f.write(file_content)
         finally:
           f.close()