Comment 5 for bug 528925

It seems to be a problem with HTTP/1.1 pipelining on Google's side. APT sends 6 requests in pipeline to the server and receives only one response:

GET /linux/deb/dists/stable/Release.gpg HTTP/1.1
Host: dl.google.com
Connection: keep-alive
If-Modified-Since: Sat, 20 Mar 2010 00:00:00 GMT
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

GET /linux/deb/dists/stable/non-free/i18n/Translation-pl.bz2 HTTP/1.1
Host: dl.google.com
Connection: keep-alive
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

GET /linux/deb/dists/stable/main/i18n/Translation-pl.bz2 HTTP/1.1
Host: dl.google.com
Connection: keep-alive
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

GET /linux/deb/dists/testing/Release.gpg HTTP/1.1
Host: dl.google.com
Connection: keep-alive
If-Modified-Since: Sat, 20 Mar 2010 00:00:00 GMT
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

GET /linux/deb/dists/testing/non-free/i18n/Translation-pl.bz2 HTTP/1.1
Host: dl.google.com
Connection: keep-alive
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

GET /linux/deb/dists/testing/main/i18n/Translation-pl.bz2 HTTP/1.1
Host: dl.google.com
Connection: keep-alive
User-Agent: Ubuntu APT-HTTP/1.3 (0.7.23.1ubuntu2)

HTTP/1.1 200 OK
Last-Modified: Sat, 20 Mar 2010 00:00:00 GMT
Accept-Ranges: bytes
Content-Length: 189
Content-Type: application/octet-stream
ETag: 12798
Vary: *
Date: Sun, 21 Mar 2010 00:05:52 GMT
Server: downloads
X-XSS-Protection: 0

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQBLpAB7oECDD3+sWZERAjWDAJ0U/RrTcNgDBndhZhzpfO8IkGTxrgCeM4g2
MTcZmYqhpJ6jreLHBW4H/F0=
=u/IL
-----END PGP SIGNATURE-----

As a workaround adding

Acquire::http::Pipeline-Depth "0";

to to a file in /etc/apt.conf.d fixes the problem for me.