avoiding depending on latest version of process except on Windows

Annex/Multicast.hs

@@ -5,6 +5,8 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE CPP #-}
+
 module Annex.Multicast where
 
 import Config.Files
@@ -14,6 +16,9 @@ import Utility.PartialPrelude
 import System.Process
 import System.IO
 import GHC.IO.Handle.FD
+#if ! MIN_VERSION_process(1,4,2)
+import System.Posix.IO (handleToFd)
+#endif
 
 multicastReceiveEnv :: String
 multicastReceiveEnv = "GIT_ANNEX_MULTICAST_RECEIVE"
@@ -21,8 +26,14 @@ multicastReceiveEnv = "GIT_ANNEX_MULTICAST_RECEIVE"
 multicastCallbackEnv :: IO (FilePath, [(String, String)], Handle)
 multicastCallbackEnv = do
 	gitannex <- readProgramFile
+#if MIN_VERSION_process(1,4,2)
+	-- This will even work on Windows
 	(rfd, wfd) <- createPipeFd
 	rh <- fdToHandle rfd
+#else
+	(rh, wh) <- createPipe
+	wfd <- handleToFd wh
+#endif
 	environ <- addEntry multicastReceiveEnv (show wfd) <$> getEnvironment
 	return (gitannex, environ, rh)