From fe98fb31b5c9f800a20d5dfa26eb95cb1f6da62d Mon Sep 17 00:00:00 2001
From: Matthew Pickering <matthewtpickering@gmail.com>
Date: Thu, 5 Nov 2020 17:23:35 +0000
Subject: [PATCH] Add note about deleting head.hackage index

---
 README.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/README.md b/README.md
index b3764e16..5e705810 100644
--- a/README.md
+++ b/README.md
@@ -85,3 +85,9 @@ There are `hspec` tests, that can be run with `cabal`:
 ```
 cabal new-build all && cabal new-test all
 ```
+
+### Unexpected Build Failures
+
+If you encounter dependencies failing to build but there's a patch for
+the library in head.hackage then you may need to delete `~/.cabal/packages/head.hackage.org`
+so that the fresh patch is visible. This is probably a bug in cabal!
-- 
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