QEMU
Given https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=822452 --roottype ext3 is needed to create wheezy QEMU image:
vmdebootstrap --verbose --serial-console --distribution=wheezy \
--customize=/usr/share/autopkgtest/setup-commands/setup-testbed \
--user=test/test --size=10000000000 --grub --roottype ext3 --convert-qcow2 \
--image=autopkgtest-wheezy.img
LXC
TODO: Network support in a wheezy container seems broken.