debconf dialog for vm not displaying properly

During the second stage processing on the virtual machine, one of the packages I seeded the build with (ez-ipupdate) wants to be configured during its Setting up stage. This seems to be attempting to use the Dialog frontend of debconf, but it doesn't display correctly (just sets part of the terminal blue). This blocks the build process, and I can't find a way onto the VM to kill the debconf process to cause the build to continue.

I know what the dialog should look like from installing the package on my machine, and hitting enter will cause it to continue, but no key combination can get the build terminal to respond, except ^C which kills the build process.

It seems like stdin is not being passed through to the VM. If this is by design, perhaps debconf could be reconfigured to Noninteractive before installing the seeded packages?

I've attached the log, in case it helps. The strange mirror address I'm passing is pointing at my local apt-cacher-ng proxy.