Move markContentsGood to after DerivationBuilder finishes

I think this should be fine for repairing. If anything, it is better,
because it would be weird to "mark and output good" only for it to then
fail output checks.

src/libstore/unix/build/derivation-builder.cc

@@ -1804,7 +1804,6 @@ SingleDrvOutputs DerivationBuilderImpl::registerOutputs()
             }
 
             store.optimisePath(actualPath, NoRepair); // FIXME: combine with scanForReferences()
-            miscMethods->markContentsGood(newInfo.path);
 
             newInfo.deriver = drvPath;
             newInfo.ultimate = true;