bug#11924: t/aclocal7.sh fails after updating from 1.12.1 to 1.12.2

[Peter Simons]

Hi,

we have recently updated from Automake 1.12.1 to 1.12.2 in the NixOS Linux
distribution. That change caused a unit test failure in t/aclocal7.sh. The
complete build log is available here:

  http://hydra.nixos.org/build/2786726

Unfortunately, the log shows very little information about the nature of that
test. It just says:

  FAIL: t/aclocal7.sh

Could someone help me out understanding exactly why that test failed and --
more importantly -- how to fix it?

Take care,
Peter