better if not present

Author: parsonsmatt

lib/call-cabal-project-to-nix.nix

@@ -231,7 +231,7 @@ let
             then fetchgit { inherit (repoData) url sha256; rev = repoData.rev or repoData.ref; }
             else
               let drv = builtins.fetchGit { inherit (repoData) url ; rev = repoData.rev or repoData.ref; ref = repoData.ref or null; };
-              in __trace "WARNING: No sha256 found for source-repository-package ${repoData.url} ref=${repoData.ref or ""} rev=${repoData.rev or ""} download may fail in restricted mode (hydra)"
+              in __trace "WARNING: No sha256 found for source-repository-package ${repoData.url} ref=${repoData.ref or "(unspecified)"} rev=${repoData.rev or "(unspecified)"} download may fail in restricted mode (hydra)"
                 (__trace "Consider adding `--sha256: ${hashPath drv}` to the ${cabalProjectFileName} file or passing in a sha256map argument"
                  drv);
         in {