--- ghc-8.2.2/libraries/Cabal/Cabal/Distribution/Simple/Install.hs~	2017-05-05 16:51:43.000000000 +0200
+++ ghc-8.2.2/libraries/Cabal/Cabal/Distribution/Simple/Install.hs	2018-01-23 23:05:47.047081056 +0100
@@ -36,7 +36,7 @@
 import Distribution.Simple.Utils
          ( createDirectoryIfMissingVerbose
          , installDirectoryContents, installOrdinaryFile, isInSearchPath
-         , die', info, noticeNoWrap, warn, matchDirFileGlob )
+         , die', info, noticeNoWrap, warn, matchDirFileGlob, debug )
 import Distribution.Simple.Compiler
          ( CompilerFlavor(..), compilerFlavor )
 import Distribution.Simple.Setup
@@ -215,7 +215,7 @@
                       ++ " in " ++ binPref)
     inPath <- isInSearchPath binPref
     when (not inPath) $
-      warn verbosity ("The directory " ++ binPref
+      debug verbosity ("The directory " ++ binPref
                       ++ " is not in the system search path.")
     case compilerFlavor (compiler lbi) of
       GHC   -> GHC.installExe   verbosity lbi binPref buildPref progFix pkg_descr exe