Don't increase the number of backticks unnecessarily

A better version of the fix in
6198bbe01e

ox-blackfriday.el

@@ -440,9 +440,9 @@ INFO is a plist used as a communication channel."
     ;;   (message "Hello")
     ;;   ```
     ;;   ````
-    (when num-backticks-in-code
-      (setq org-blackfriday--code-block-num-backticks
-            (1+ (max num-backticks-in-code org-blackfriday--code-block-num-backticks))))
+    (when (and (numberp num-backticks-in-code)
+               (<= org-blackfriday--code-block-num-backticks num-backticks-in-code))
+      (setq org-blackfriday--code-block-num-backticks (1+ num-backticks-in-code)))
     (setq backticks (make-string org-blackfriday--code-block-num-backticks ?`))
     ;; (message "[ox-bf src-block DBG]")
     ;; (message "ox-bf [dbg] code: %s" code)

test/site/content-org/all-posts.org

@@ -504,26 +504,43 @@ fenced code blocks.*
 :EXPORT_HUGO_CODE_FENCE: t
 :EXPORT_FILE_NAME: code-fenced-src-blocks-with-backticks
 :END:
-This code block is fenced with 4 backticks:
+This code block contains a fenced code block with 4 backticks:
 #+BEGIN_SRC md
 ````emacs-lisp
 (message "Hello")
 ````
 #+END_SRC
 
-This code block is fenced with 3 backticks:
+This code block contains a fenced code block with 3 backticks:
 #+BEGIN_SRC md
 ```emacs-lisp
 (message "Hello again")
 ```
 #+END_SRC
 
-This code block is fenced again with 4 backticks:
+This code block contains no backticks:
+#+BEGIN_SRC emacs-lisp
+(message "Hello again x2")
+#+END_SRC
+
+This code block again contains a fenced code block with 4 backticks:
 #+BEGIN_SRC md
 ````emacs-lisp
-(message "Hello again, again")
+(message "Hello again x3")
 ````
 #+END_SRC
+
+This code block contains a fenced code block with 6 backticks:
+#+BEGIN_SRC md
+``````emacs-lisp
+(message "Hello again x4")
+``````
+#+END_SRC
+
+This code block once again contains no backticks:
+#+BEGIN_SRC emacs-lisp
+(message "Hello again x6")
+#+END_SRC
 ** Highlight Shortcode                                  :highlight:shortcode:
 *** Source blocks with =highlight= shortcode
 :PROPERTIES:

test/site/content/posts/code-fenced-src-blocks-with-backticks.md

@@ -4,7 +4,7 @@ tags = ["src-block", "code-fence", "backticks"]
 draft = false
 +++
 
-This code block is fenced with 4 backticks:
+This code block contains a fenced code block with 4 backticks:
 
 `````md
 ````emacs-lisp
@@ -12,18 +12,38 @@ This code block is fenced with 4 backticks:
 ````
 `````
 
-This code block is fenced with 3 backticks:
+This code block contains a fenced code block with 3 backticks:
 
-``````md
+`````md
 ```emacs-lisp
 (message "Hello again")
 ```
-``````
+`````
 
-This code block is fenced again with 4 backticks:
+This code block contains no backticks:
 
-```````md
+`````emacs-lisp
+(message "Hello again x2")
+`````
+
+This code block again contains a fenced code block with 4 backticks:
+
+`````md
 ````emacs-lisp
-(message "Hello again, again")
+(message "Hello again x3")
 ````
+`````
+
+This code block contains a fenced code block with 6 backticks:
+
+```````md
+``````emacs-lisp
+(message "Hello again x4")
+``````
+```````
+
+This code block once again contains no backticks:
+
+```````emacs-lisp
+(message "Hello again x6")
 ```````