All dependencies do not need to be specified when using debootstrap. The only packages we need to list explicitly in 01-packages-gce are the ones we specifically care about; dependencies will be handled automatically.

Similarly, the only packages we need to list in 13-prefer-backports-packages are the ones which need to come from backports rather than the regular wheezy archive. Unlisted dependencies will be pulled as needed from (non-backports) wheezy.