From a1f69b1c7d6622a3bee678eb01ba36e94b99cd20 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Thu, 14 Nov 2019 05:46:56 -0800
Subject: Fix regression preventing header-includes from being set using -V.

See #5904.
---
 src/Text/Pandoc/App/OutputSettings.hs | 3 ++-
 test/command/5904.md                  | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 test/command/5904.md

diff --git a/src/Text/Pandoc/App/OutputSettings.hs b/src/Text/Pandoc/App/OutputSettings.hs
index d328a9b6a..77248cab1 100644
--- a/src/Text/Pandoc/App/OutputSettings.hs
+++ b/src/Text/Pandoc/App/OutputSettings.hs
@@ -117,7 +117,8 @@ optToOutputSettings opts = do
 
   let setVariableM k v = return . setVariable k v
 
-  let setListVariableM k vs =
+  let setListVariableM _ [] = return
+      setListVariableM k vs =
         return . Context .
           (M.insert (T.pack k) (toVal $ map T.pack vs)) . unContext
 
diff --git a/test/command/5904.md b/test/command/5904.md
new file mode 100644
index 000000000..fdc29407d
--- /dev/null
+++ b/test/command/5904.md
@@ -0,0 +1,8 @@
+```
+%  pandoc -s -t markdown -H test/B.txt --variable header-includes:foo
+Hi
+^D
+foo
+
+Hi
+```
-- 
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