Select method returns a file descriptor.

So it needs to write the file content in the correct path which must
be used by buildout.

src/zc/buildout/networkcache.py

@@ -72,14 +72,14 @@ def download_network_cached(dir_url, cache_url, path, url, logger, md5sum=None):
     logger.info('Downloading %s from network cache.' % file_name)
     try:
         nc = NetworkcacheClient(shacache=cache_url, shadir=dir_url)
-        file_content = nc.select(directory_key)
-
+        file_descriptor = nc.select(directory_key)
         f = open(path, 'w+b')
         try:
-          f.seek(0)
-          f.write(file_content)
+          for line in file_descriptor:
+            f.write(line)
         finally:
           f.close()
+          file_descriptor.close()
 
         if not check_md5sum(path, md5sum):
             logger.info('MD5 checksum mismatch downloading %s' % file_name)