### Please describe the problem.

Using `copy --destdir=<path>` fails.

### What steps will reproduce the problem?

~~~
% ./Setup.hs configure --prefix=/usr
% ./Setup.hs build
% ./Setup.hs copy --destdir=my/pkg/dir
~~~

### What version of git-annex are you using? On what operating system?

5.20150731 on Linux (Arch Linux)

### Please provide any additional information below.

The steps in `myPostCopy` doesn't consider the destination directory, the following change is enough for my uses:

~~~
Index: habs/git-annex/src/git-annex-5.20150731/Setup.hs
===================================================================
--- habs.orig/git-annex/src/git-annex-5.20150731/Setup.hs
+++ habs/git-annex/src/git-annex-5.20150731/Setup.hs
@@ -27,13 +27,13 @@ main = defaultMainWithHooks simpleUserHo
 	}
 
 myPostCopy :: Args -> CopyFlags -> PackageDescription -> LocalBuildInfo -> IO ()
-myPostCopy _ (CopyFlags { copyVerbosity }) pkg lbi = do
+myPostCopy _ flags pkg lbi = do
 	installGitAnnexShell dest verbosity pkg lbi
 	installManpages      dest verbosity pkg lbi
-	installDesktopFile   dest verbosity pkg lbi
+	-- installDesktopFile   dest verbosity pkg lbi
   where
-	dest      = NoCopyDest
-	verbosity = fromFlag copyVerbosity
+	dest      = fromFlag $ copyDest flags
+	verbosity = fromFlag $ copyVerbosity flags
 
 installGitAnnexShell :: CopyDest -> Verbosity -> PackageDescription -> LocalBuildInfo -> IO ()
 installGitAnnexShell copyDest verbosity pkg lbi =
~~~

As you see I commented out installation of desktop files completely for the moment.  I don't really need them, and they require larger changes to be correct.

> So, by "fails", you mean it installs to ~/.cabal instead of the speficied
> location.
> 
> And, the issue with the desktop file installation is that it's not inside
> ~/.cabal at all.
> 
> I've applied your patch, thanks. And dealt with the desktop file by
> making it not install it anywhere, unless it's installing to the regular
> ~/.cabal location. [[done]] --[[Joey]]