fix result copy in case of build failure.

src/Argonix.hs

@@ -415,13 +415,13 @@ wrap nixCommand target sa@ArgsCommon {..} = do
   putText $ nixc <> " " <> T.unwords arglist
   case nixCommand of
     NixShell -> executeFile (toS nixc) True (fmap toS arglist) Nothing
-    NixBuild ->
-      P.runProcess_
+    NixBuild -> do
+      _ <- P.runProcess
           (P.setEnv (fmap (\(x, y) -> (toS x, toS y)) envVars)
                     (P.proc (toS nixc) $ fmap toS arglist)
           )
-        <> runProcessVerbose verbosity "cp" ["-r", "/tmp/papa", "./result"] []
-        <> runProcessVerbose verbosity "cp" ["-r", toS tmpXDGHOME, "./nixtmpdir"] []
+      runProcessVerbose verbosity "cp" ["-r", "/tmp/papa", "./result"] []
+      runProcessVerbose verbosity "cp" ["-r", toS tmpXDGHOME, "./nixtmpdir"] []
  where
   nixc = toCommand nixCommand
   arglist =