Fixes <https://bugs.gnu.org/33297>. Reported by Mark H Weaver <mhw@netris.org>. This fixes a regression introduced in 72dc64f8f720268930eed448abfc15d2a0eca3cf, which made files read-only. * gnu/build/linux-initrd.scm (build-initrd): Call 'make-file-writable' on all the files under contents/.