Bug#659064: full story
Okay, here the whole story as I understand it.
The OP bootstrapped a Squeeze system. This includes the
./lib64 -> /lib symlink.
After that, the OP bootstrapped a Wheezy system over the existing
Squeeze root. This includes the dir ./lib64 and the symlink
./lib64/ld-linux-x86-64.so.2 in the tar file of the libc6 package. After
the bootstrap, the system dynamic linker was overwritten.
The old tar accepts that ./lib64 exists and overwrites
/lib/ld-linux-x86-64.so.2 in the process. Current tar seems to remove
the symlink first if it wants to extract a directory, so this should not
longer happen with the tar in Wheezy.
Because neither dpkg, nor any of the bootstrap tools handles the case of
symlink vs. directory correctly, there was an informal decision,
including the release team, that base packages just should not do that.
Now I'm told that you decided to change the variables of this problem by
actually turning lib64 into a directory.
History tends to exaggerate.
-- Col. Green, "The Savage Curtain", stardate 5906.4