patch 9.1.0033: Insert mode not stopped if closing prompt buffer modifies hidden buffer

Problem:  Insert mode not stopped if an autocommand modifies a hidden
          buffer while closing a prompt buffer.
Solution: Don't set b_prompt_insert if stop_insert_mode is already set.
          (zeertzjq)

closes: #13872

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    33,
 /**/
     32,
 /**/