I don't think squid is to blame here:
HEAD -p http://squid.internal:3128/ ftp://ftp.uvsq.fr/pub/ubuntu/releases/8.04/MD5SUMS 200 OK
HEAD -p http://squid.internal:3128/ ftp://ftp.uvsq.fr/pub/ubuntu/releases/8.04/MD5SUMS2 404 Not Found
HEAD -p http://squid.internal:3128/ ftp://ftp.uvsq.fr/pub/ubuntu/releases/8.05/MD5SUMS2 404 Not Found
As you see, we get a 404 when the dir doesn't exist as well.
I don't think squid is to blame here:
HEAD -p http:// squid.internal: 3128/ ftp://ftp. uvsq.fr/ pub/ubuntu/ releases/ 8.04/MD5SUMS
200 OK
HEAD -p http:// squid.internal: 3128/ ftp://ftp. uvsq.fr/ pub/ubuntu/ releases/ 8.04/MD5SUMS2
404 Not Found
HEAD -p http:// squid.internal: 3128/ ftp://ftp. uvsq.fr/ pub/ubuntu/ releases/ 8.05/MD5SUMS2
404 Not Found
As you see, we get a 404 when the dir doesn't exist as well.