From e479c6473c0dfd181b2bc980ab9c4447789bb066 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Tue, 29 Jan 2013 16:25:20 +0200
Subject: [PATCH] Ensure unique list of build tools

---
 Stackage/Select.hs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Stackage/Select.hs b/Stackage/Select.hs
index 804d7081..caf24c40 100644
--- a/Stackage/Select.hs
+++ b/Stackage/Select.hs
@@ -49,6 +49,8 @@ iiBuildTools InstallInfo { iiPackageDB = PackageDB m, iiPackages = packages } =
   $ topSort
   $ map addDependencies
   $ filter (flip Set.notMember coreTools . fst)
+  $ Set.toList
+  $ Set.fromList
   $ mapMaybe (flip Map.lookup buildToolMap)
   $ Set.toList
   $ Set.unions