fix warnings

Annex/Environment.hs

@@ -14,7 +14,6 @@ import Utility.UserInfo
 import qualified Git.Config
 
 import System.Posix.Env
-import Network.BSD
 
 {- Checks that the system's environment allows git to function.
  - Git requires a GECOS username, or suitable git configuration, or

Utility/FileMode.hs

@@ -10,7 +10,6 @@ module Utility.FileMode where
 import Common
 
 import Control.Exception (bracket)
-import Utility.Exception
 import System.Posix.Types
 import Foreign (complement)