Some of the permiessions of directories at tinderbox.dev.gentoo.org don't allow reading those. For example, it is impossible to download a binary version of GCC for ARMv7-softfp, because of HTTP 403 error at http://tinderbox.dev.gentoo.org/default-linux/arm/armv7a-softfp-linux-gnueabi/stable/sys-devel/
That was because the repository wasn't fully updated. Anyway that doesn't matter now, the machine just died.