Just an important note for anybody ending up at this bug and wanting to remove libc6-amd64. As long as you have root access to the system and have not powered off yet, I believe you can fix this issue without rescue CD/USB.
With root access (sudo does not work anymore, because the setguid fails) you can do: apt-get remove libc6-amd64 cd lib64 /lib/x86_64-linux-gnu/ld-2.13.so /bin/rm ld-linux-x86-64.so.2 /lib/x86_64-linux-gnu/ld-2.13.so /bin/ln -s /lib/x86_64-linux-gnu/ld-2.13.so ld-linux-x86-64.so.2 Done. I haven't tested this sequence (as I did not have a root login available) but I am pretty sure this would work. Paul
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