glog: patch /usr/bin/true in tests

Tests appear to use `/usr/bin/true` as a fake mailer, which causes an
error in the check phase. This does not cause the tests to fail, and
this is why the replace is a warn and not fail. Patching it nonetheless.

Author: Pleune

pkgs/by-name/gl/glog/package.nix

@@ -6,6 +6,7 @@
   gflags,
   gtest,
   perl,
+  coreutils,
 }:
 
 stdenv.mkDerivation rec {
@@ -19,6 +20,11 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-+nwWP6VBmhgU7GCPSEGUzvUSCc48wXME181WpJ5ABP4=";
   };
 
+  postPatch = ''
+    substituteInPlace src/logging_unittest.cc \
+      --replace-warn "/usr/bin/true" "${coreutils}/bin/true"
+  '';
+
   nativeBuildInputs = [ cmake ];
 
   buildInputs = [ gtest ];