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With version 3.3 (64 bit on Arch Linux) Python now hangs when closing FTP connection on some sites:
url = "ftp://ftp.fu-berlin.de/pub/misc/movies/database/ratings.list.gz"
with urllib.request.urlopen( url ):
	pass

I guess this is about urllib, not ftplib.

Well, urllib calls ftplib for ftp urls, so it might be about ftplib. But in that case it would be better to have a reproducer that *just* uses ftplib.

I can reproduce the issue on python 3.3.
To have a clearer understanding on what's going on use:
import urllib.request
import ftplib
ftplib.FTP.debugging = 4
url = "ftp://ftp.fu-berlin.de/pub/misc/movies/database/ratings.list.gz"
with urllib.request.urlopen(url):
 pass
The problem appears to be endtransfer() erroneously calling ftp.voidresp() (it just shouldn't):
http://hg.python.org/cpython/file/f6fcff683866/Lib/urllib/request.py#l2328
Patch in attachment fixes the issue.

New changeset edeeb727df86 by Giampaolo Rodola' in branch 'default':
Fix issue #16270: urllib may hang when used for retrieving files via FTP by using a context manager.
http://hg.python.org/cpython/rev/edeeb727df86 

New changeset 2e6bcbb0ff59 by Giampaolo Rodola' in branch '3.3':
Fix issue #16270: urllib may hang when used for retrieving files via FTP by using a context manager.
http://hg.python.org/cpython/rev/2e6bcbb0ff59 

New changeset 7f0d9637a3ad by Giampaolo Rodola' in branch '3.2':
Fix issue #16270: urllib may hang when used for retrieving files via FTP by using a context manager.
http://hg.python.org/cpython/rev/7f0d9637a3ad 

New changeset 44d02a5d59fb by Senthil Kumaran in branch '2.7':
Closes issue26960.
https://hg.python.org/cpython/rev/44d02a5d59fb 

The original problem here was retrieving files failed (hung) when it was tried via context-manager
1. For e.g after "reverting" the changes, if you use the original file without the context manager, it will succeed.
fobj = urllib.request.urlopen( url )
That indicates the fix in changing something in endtransfer method was improper. I have given more information here: http://bugs.python.org/issue27973#msg286016
The proper fix will be revert the endtransfer changes, but fix it in contextmanager scenario. Add test cases to cover all these scenarios.