these 5 derivations will be built:
  /nix/store/7fx0rza5rvzb595y6yihdlg9dv4z2lnq-tree_style_tab-4.4.4.xpi.drv
  /nix/store/prqdnqlqys0hfi6ix056h9z4qsm94fy8-tree-style-tab-4.4.4.drv
  /nix/store/6nihdzxd6h255h0a77av9lc4jsf4shdj-hm-firefox-extensions.drv
  /nix/store/km3m0f9i0r401pm7yz24x66cgx5h51q2-home-manager-files.drv
  /nix/store/ar2n8320jr1lx72hpssnwxb769g5rn6q-home-manager-generation.drv