Bug#316337: Proof

[roan.kattouw@home.nl]

I ran strace -ff on an bzip2-error-spewing apt-get update, and came
across one of the following traces (for a bzip2 subprocess):

dup2(3, 0) = 0
/* ... */
execve("/usr/bin/bzip2", ["bzip2", "-d"], [/* 28 vars */]) = 0
/* ... */
read(0, "", 65536)                      = 0
read(0, "", 65536)                      = 0
write(2, "\nbzip2: Compressed file ends une"..., 97) = 97
write(2, "bzip2: Function not implemented\n", 32) = 32
write(2, "\tInput file = (stdin), output fi"..., 46) = 46
write(2, "\nIt is possible that the compres"..., 240) = 240
exit_group(2)                           = ?

This proves that bzip2 is really fed an empty file. In the traces for
one of the methods/ftp subprocesses I found:

open("/var/lib/apt/lists/partial/ftp.debian.nl_debian_dists_stable_main_binary-i
386_Packages", O_RDONLY) = 3
fcntl64(3, F_SETFD, FD_CLOEXEC) = 0
pipe([4, 5]) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, chil
d_tidptr=0xb7cd4708) = 7029

This proves that the empty file bzip2 is fed is really a
/var/lib/apt/lists/partial/* file.