Windows: Fix handling of absolute unix-style git repository paths.

Note that on Windows a remote with a path like /home/foo/bar
is interpreted by git as being some screwy relative path (relative to what
exactly seems ill-defined -- it seemed relative to C:\Program Files\Git\ in
my tests!) So no attempt has been made to handle such a path sanely, just not
to crash when encountering it.

Note that "C:\\foo" </> "/home/foo/bar" yields /home/foo/bar even though
that is not absolute! I don't know what to make of all this,
except that I will be very happy when this crock of **** vanishes from
the face of the earth.

Git/Construct.hs

@@ -33,6 +33,7 @@ import Common
 import Git.Types
 import Git
 import Git.Remote
+import Git.FilePath
 import qualified Git.Url as Url
 import Utility.UserInfo
 
@@ -57,7 +58,7 @@ fromPath dir = fromAbsPath =<< absPath dir
  - specified. -}
 fromAbsPath :: FilePath -> IO Repo
 fromAbsPath dir
-	| isAbsolute dir = ifM (doesDirectoryExist dir') ( ret dir' , hunt )
+	| absoluteGitPath dir = ifM (doesDirectoryExist dir') ( ret dir' , hunt )
 	| otherwise =
 		error $ "internal error, " ++ dir ++ " is not absolute"
   where