Comment 15 for bug 1172101

Oh! I just spotted the problem here. When running in d-i, debootstrap uses base-installer/pkgdetails.c to provide progress output. That looks for anything vaguely like a percentage, which matches the URL-encoded colon ("%3a").

I still have some work to do for this, but it has my attention now that I've figured out that particularly inscrutable failure.