trivial-builders: merge passAsFile with env in runCommand'

Previously it was awkward to use the runCommand-variants with
passAsFile as a double definition of passAsFile would potentially
break runCommand: passAsFile would overwrite the previous definition,
defeating the purpose of setting it in runCommand in the first place.
This is now fixed by concatenating the [ "buildCommand" ] list with
one the one from env, if present.

Adjust buildEnv where passAsFile = null; was passed in some cases,
breaking evaluation since it'd evaluate to [ "buildCommand" ] ++ null.

1 files changed, 1 insertions, 1 deletions

diff --git a/pkgs/build-support/buildenv/default.nix b/pkgs/build-support/buildenv/default.nix
index 5fafc36273a..c2186cf6bfa 100644
--- a/pkgs/build-support/buildenv/default.nix
+++ b/pkgs/build-support/buildenv/default.nix
@@ -74,7 +74,7 @@ runCommand name
     preferLocalBuild = true;
     allowSubstitutes = false;
     # XXX: The size is somewhat arbitrary
-    passAsFile = if builtins.stringLength pkgs >= 128*1024 then [ "pkgs" ] else null;
+    passAsFile = if builtins.stringLength pkgs >= 128*1024 then [ "pkgs" ] else [ ];
   }
   ''
     ${buildPackages.perl}/bin/perl -w ${builder}