Markdown writer: Ensure the code fence is long enough.

Previously too few backticks were used when the code block
contained an indented line of backticks.  (Ditto tildes.)

Cloess #5519.

1 files changed, 14 insertions, 0 deletions

diff --git a/test/command/5519.md b/test/command/5519.md
new file mode 100644
index 000000000..a175ce9f9
--- /dev/null
+++ b/test/command/5519.md
@@ -0,0 +1,14 @@
+~~~
+% pandoc -t markdown
+``````{.attr}
+ ```
+ code
+ ```
+``````
+^D
+```` {.attr}
+ ```
+ code
+ ```
+````
+~~~