Markdown reader/writer: spacing adjustments in tables.

* Markdown writer now includes a blank line at the end
  of the row in a single-row multiline table, to prevent it from being
  interpreted as a simple table.  Closes #4578.
* Markdown reader does a better job computing the relative width of
  the last column in a multiline table, so we can round-trip tables
  without constantly shrinking the last column.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 3bfa8a012..075858e5e 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -732,7 +732,10 @@ pandocTable opts multiline headless aligns widths rawHeaders rawRows = do
                   then empty
                   else border <> cr <> head'
   let body = if multiline
-                then vsep rows'
+                then vsep rows' $$
+                     if length rows' < 2
+                        then blankline -- #4578
+                        else empty
                 else vcat rows'
   let bottom = if headless
                   then underline