Avoid unnecessarily looking up StackageId in haddock unpacker

Handler/Haddock.hs

@@ -314,8 +314,7 @@ createHaddockUnpacker root store runDB' urlRenderRef = do
                 -- Determine which packages have documentation and update the
                 -- database appropriately
                 runResourceT $ runDB' $ do
-                    ment <- getBy $ UniqueStackage ident
-                    forM_ ment $ \(Entity sid _) -> do
+                    let sid = entityKey stackageEnt
                     updateWhere
                         [PackageStackage ==. sid]
                         [PackageHasHaddocks =. False]