bug#36754: New linux-libre failed to build on armhf on Berlin

[Mark H Weaver]

In commit 1ad9c105c208caa9059924cbfbe4759c8101f6c9, I changed our
linux-libre packages to deblob the linux-libre source tarballs
ourselves, i.e. to run the deblobbing scripts provided by the
linux-libre project to produce linux-libre source tarballs from the
upstream linux tarballs:

  
https://git.savannah.gnu.org/cgit/guix.git/commit/?id=1ad9c105c208caa9059924cbfbe4759c8101f6c9

The following queries show that the updated packages built successfully
on x86_64, i686, and aarch64, but they all failed on armhf:

  https://ci.guix.gnu.org/search?query=linux-libre-5.2.2
  https://ci.guix.gnu.org/search?query=linux-libre-4.19.60
  https://ci.guix.gnu.org/search?query=linux-libre-4.14.134
  https://ci.guix.gnu.org/search?query=linux-libre-4.9.186
  https://ci.guix.gnu.org/search?query=linux-libre-4.4.186
  https://ci.guix.gnu.org/search?query=linux-libre-arm-veyron-5.2.2
  https://ci.guix.gnu.org/search?query=linux-libre-arm-generic-5.2.2
  https://ci.guix.gnu.org/search?query=linux-libre-arm-generic-4.19.60
  https://ci.guix.gnu.org/search?query=linux-libre-arm-generic-4.14.134
  https://ci.guix.gnu.org/search?query=linux-libre-arm-omap2plus-5.2.2
  https://ci.guix.gnu.org/search?query=linux-libre-arm-omap2plus-4.19.60
  https://ci.guix.gnu.org/search?query=linux-libre-arm-omap2plus-4.14.134

Unfortunately, I'm unable to get *any* information about what went wrong
from Cuirass.  None of the failed builds have associated log files, and
the build details page has no useful information either.  For example:

  https://ci.guix.gnu.org/build/1488517/details

My first guess was that something went wrong in the 'computed' origin
that runs the deblobbing script.  However, that's apparently not the
case, because all of the updated 'linux-libre-headers' packages built
successfully on armhf, and those use the same source tarballs as the
main 'linux-libre' packages.

  https://ci.guix.gnu.org/search?query=linux-libre-headers-5.2.2
  https://ci.guix.gnu.org/search?query=linux-libre-headers-4.19.60
  https://ci.guix.gnu.org/search?query=linux-libre-headers-4.14.134

Can someone help me find out what's going on here?  Until then, I'm
sorry to say that armhf-linux users will be unable to update their
systems.

       Mark