Biblio: Workaround broken toCapital in citeproc-0.3.4.

src/Text/Pandoc/Biblio.hs

@@ -92,8 +92,16 @@ mvPunct (Space : x : ys) | isNote x = x : ys
 mvPunct xs = xs
 
 sanitize :: [Inline] -> [Inline]
-sanitize xs | endWithPunct xs = toCapital xs
-            | otherwise       = toCapital (xs ++ [Str "."])
+sanitize xs | endWithPunct xs = toCapital' xs
+            | otherwise       = toCapital' (xs ++ [Str "."])
+
+-- NOTE: toCapital' works around a bug in toCapital from citeproc-hs 0.3.4.
+-- When citeproc-hs is fixed, we can return to using toCapital in sanitize.
+toCapital' :: [Inline] -> [Inline]
+toCapital' [] = []
+toCapital' xs = case toCapital xs of
+                       [] -> xs
+                       ys -> ys
 
 deNote :: [Block] -> [Block]
 deNote = topDown go