In the sandbox built for https://nixbuild.net, the coreutils build fails
because a failure in the df skip-rootfs test. The test failure is triggered by
the existance of a rootfs file system. However, I think that the test is faulty,
and I have reported it upstream in
https://lists.gnu.org/archive/html/bug-coreutils/2019-12/msg00000.html.
Disabling the test makes the coreutils build work in the nixbuild.net sandbox,
and I can't think of any negative impact disabling it can have. In normal nix
setups and in the normal nix sandbox, this test is not exercised anyway, since
there is no rootfs visible.
28f2dcc8b7