WIP: Add man page installation to Setup.hs

This works with `cabal-dev install .`, but `cabal sdist` does not yet
include the man pages (tried adding a `make $(mans)` before `cabal
sdist` in `make sdist`, but no luck).

XXX: Need to go back and replace spaces with tabs.

Setup.hs

@@ -3,6 +3,9 @@
 import Distribution.Simple
 import Distribution.Simple.LocalBuildInfo
 import Distribution.Simple.Setup
+import Distribution.Simple.Utils (installOrdinaryFiles)
+import Distribution.PackageDescription (PackageDescription(..))
+import Distribution.Verbosity (Verbosity)
 import System.Cmd
 import System.FilePath
 
@@ -11,6 +14,7 @@ import qualified Build.Configure as Configure
 main = defaultMainWithHooks simpleUserHooks
 	{ preConf = configure
 	, instHook = install
+        , postInst = const installManpages
 	}
 
 configure _ _ = do
@@ -25,3 +29,23 @@ install pkg_descr lbi userhooks flags = do
 	where
 		installDirs = absoluteInstallDirs pkg_descr lbi $
 			fromFlag (copyDest defaultCopyFlags)
+
+-- See http://www.haskell.org/haskellwiki/Cabal/Developer-FAQ#Installing_manpages.
+--
+-- Based on pandoc's 'Setup.installManpages' and 'postInst' hook.
+-- Would be easier to just use 'rawSystem' as above.
+--
+-- XXX: fix tabs!
+installManpages :: InstallFlags -> PackageDescription -> LocalBuildInfo -> IO ()
+installManpages flags pkg lbi =
+  installOrdinaryFiles verbosity dstManDir manpages
+  where
+    srcManDir = ""
+    -- The 'NoCopyDest' means "don't add an additional path prefix".
+    -- The pandoc Setup.hs uses 'NoCopyDest' in the post install hook
+    -- and the 'CopyDest' from the copy flags in the post copy hook.
+    dstManDir = mandir (absoluteInstallDirs pkg lbi NoCopyDest) </> "man1"
+    manpages  = zip (repeat srcManDir)
+                    [ "git-annex.1"
+                    , "git-annex-shell.1" ]
+    verbosity = fromFlag $ installVerbosity flags