Markdown writer: ensure blank between raw block and normal content.

Otherwise a raw block can prevent a paragraph from being
recognized as such.

Closes #4629.

src/Text/Pandoc/Writers/Markdown.hs

@@ -847,6 +847,13 @@ blockListToMarkdown opts blocks = do
            Plain ils : fixBlocks bs
       fixBlocks (Plain ils : bs) =
            Para ils : fixBlocks bs
+      fixBlocks (r@(RawBlock f raw) : b : bs)
+        | not (null raw)
+        , last raw /= '\n' =
+        case b of
+             Plain{}    -> r : fixBlocks (b:bs)
+             RawBlock{} -> r : fixBlocks (b:bs)
+             _          -> RawBlock f (raw ++ "\n") : fixBlocks (b:bs) -- #4629
       fixBlocks (x : xs)             = x : fixBlocks xs
       fixBlocks []                   = []
       isListBlock (BulletList _)     = True

test/command/macros.md

@@ -4,6 +4,7 @@
 $\my+\my$
 ^D
 \newcommand{\my}{\phi}
+
 $\phi+\phi$
 ```
 
@@ -13,6 +14,7 @@ $\phi+\phi$
 $\my+\my$
 ^D
 \newcommand{\my}{\phi}
+
 $\my+\my$
 ```
 
@@ -75,6 +77,7 @@ x &= y\\\end{aligned}\]
 \end{equation}
 ^D
 \newcommand{\my}{\phi}
+
 \begin{equation}
 \phi+\phi
 \end{equation}
@@ -88,6 +91,7 @@ x &= y\\\end{aligned}\]
 \end{equation}
 ^D
 \newcommand{\my}{\phi}
+
 \begin{equation}
 \my+\my
 \end{equation}

test/writer.markdown

@@ -409,6 +409,7 @@ And this is **strong**
 </tr>
 </table>
 <script type="text/javascript">document.write('This *should not* be interpreted as markdown');</script>
+
 Here's a simple block:
 
 <div>
@@ -446,6 +447,7 @@ foo
 This should just be an HTML comment:
 
 <!-- Comment -->
+
 Multiline:
 
 <!--
@@ -455,6 +457,7 @@ Blah
 <!--
     This is another comment.
 -->
+
 Code block:
 
     <!-- Comment -->
@@ -462,6 +465,7 @@ Code block:
 Just plain comment, with trailing spaces on the line:
 
 <!-- foo -->
+
 Code:
 
     <hr />