Hello guix, Hello Ludo

When trying to build coreutils for i686-pc-gnu, building
cross-gcc-4.8.3 with glibc-hurd fails with:

In unknown file:
   ?: 0 [string-append
"/gnu/store/1hl59s1pikplwfgclw4mlk38pkx3pc72-glibc-hurd-cross-i686-pc-gnu-2.18"
...]

ERROR: In procedure string-append:
ERROR: In procedure string-append: Wrong type (expecting string): #f

It shouldn't fail because glibc/hurd is in the path.

Checking the patch-source-shebangs phase, in the build log, shows that
the /bin/sh path is changed to use the native glibc, which I believe causes
the problem.

I am trying to understand and solve this, but I think I am
missing something from the building procedure of coreutils, so any
advice will be helpful. Why it doesn't use the glibc that it just cross-built?

I am attaching the build log and the env vars.

Thank you,
Manolis