nixVersions.nixComponents_2_27: fix error message (#398448)

pkgs/tools/package-management/nix/default.nix

···
         ) (lib.range 4 23)
       )
       // {
-        nixComponents_2_27 = throw "nixComponents_2_27 has been removed. use nixComponents_2_28.";
+        nixComponents_2_27 = throw "nixComponents_2_27 has been removed. use nixComponents_git.";
         nix_2_27 = throw "nix_2_27 has been removed. use nix_2_28.";
         nix_2_25 = throw "nix_2_25 has been removed. use nix_2_28.";