Revert "Not passing package db flags in default case"

This reverts commit 76e5af817a.

Language/Haskell/GhcMod/CabalHelper.hs

@@ -101,10 +101,7 @@ withCabal action = do
     opts <- options
     liftIO $ whenM (isSetupConfigOutOfDate <$> getCurrentWorld crdl) $
         withDirectory_ (cradleRootDir crdl) $ do
-            let pkgDbStack = cradlePkgDbStack crdl
-                pkgDbArgs = if pkgDbStack == defaultPkgDbStack
-                            then []
-                            else "--package-db=clear" : map pkgDbArg pkgDbStack
+            let pkgDbArgs = "--package-db=clear" : map pkgDbArg (cradlePkgDbStack crdl)
                 progOpts =
                     [ "--with-ghc=" ++ T.ghcProgram opts ]
                     -- Only pass ghc-pkg if it was actually set otherwise we
@@ -121,6 +118,3 @@ pkgDbArg :: GhcPkgDb -> String
 pkgDbArg GlobalDb      = "--package-db=global"
 pkgDbArg UserDb        = "--package-db=user"
 pkgDbArg (PackageDb p) = "--package-db=" ++ p
-
-defaultPkgDbStack :: [GhcPkgDb]
-defaultPkgDbStack = [GlobalDb, UserDb]