Muse reader: accept Emacs Muse definition lists

Emacs Muse does not require indentation.

src/Text/Pandoc/Readers/Muse.hs

@@ -423,7 +423,8 @@ definitionListItem = try $ do
   pure $ do lineContent' <- lineContent
             pure (B.text term, [lineContent'])
   where
-    termParser = many1 spaceChar >> -- Initial space as required by Amusewiki, but not Emacs Muse
+    termParser = (guardEnabled Ext_emacs <|> void spaceChar) >> -- Initial space is required by Amusewiki, but not Emacs Muse
+                 many spaceChar >>
                  many1Till anyChar (lookAhead (void (try (spaceChar >> string "::")) <|> void newline))
     endOfInput = try $ skipMany blankline >> skipSpaces >> eof
     twoBlankLines = try $ blankline >> skipMany1 blankline

test/Tests/Readers/Muse.hs

@@ -16,6 +16,10 @@ muse = purely $ \s -> do
   setOutputFile (Just "out")
   readMuse def s
 
+emacsMuse :: Text -> Pandoc
+emacsMuse = purely $ readMuse def { readerExtensions =
+              enableExtension Ext_emacs pandocExtensions }
+
 infix 4 =:
 (=:) :: ToString c
      => String -> (Text, c) -> TestTree
@@ -622,6 +626,14 @@ tests =
           , "Foo :: bar"
           ] =?>
         para "First :: second Foo :: bar"
+      , test emacsMuse "Emacs Muse definition list"
+        (T.unlines
+          [ "First :: second"
+          , "Foo :: bar"
+          ] =?>
+        definitionList [ ("First", [ para "second" ])
+                       , ("Foo", [ para "bar" ])
+                       ])
       , "Definition list" =:
         T.unlines
           [ " First :: second"