Allow builders to create activities

Actually, currently they can only create download activities. Thus,
downloads by builtins.fetchurl show up in the progress bar.

1 files changed, 1 insertions, 0 deletions

diff --git a/shell.nix b/shell.nix
index 435399f0b..2b4d0dd20 100644
--- a/shell.nix
+++ b/shell.nix
@@ -18,6 +18,7 @@ with import ./release-common.nix { inherit pkgs; };
         customMemoryManagement = false;
       })
       autoreconfHook
+      nlohmann_json
 
       # For nix-perl
       perl