Fixed #23920 -- Fixed MySQL crash when adding blank=True to TextField.

Thanks wkornewald for the report and Markus Holtermann for review.

tests/schema/models.py

@@ -171,3 +171,7 @@ class Thing(models.Model):
 
     def __str__(self):
         return self.when
+
+
+class Note(models.Model):
+    info = models.TextField()