If you get this error, it can seemingly be fixed by commenting out all your sources (in /etc/apt/sources.list, and possibly in /etc/apt/sources.list.d) and doing an 'apt-get update', then uncommenting them and 'apt-get update'-ing again.

Which really isn't so much a "fix", as it is a workaround, but hey, it works! I'm ok with it being magic for now.

As a side-note, if you're running etch, you want the git from the etch-backports repository (which started this whole mess for me). The etch stable version is 1.4.4, which appears to have a slightly different command set -- ie, 'git init' does not work. That was enough for me to want to make sure I'm using the latest. Not sure if there's incompatibilities between old and new versions of git, but no sense in taking any chances.