BUG Tweak DBHTMLText::Plain to avoid treating some chinese characters as line breaks.

src/ORM/FieldType/DBHTMLText.php

@@ -228,7 +228,7 @@ class DBHTMLText extends DBText
         $text = strip_tags($text);
 
         // Implode >3 consecutive linebreaks into 2
-        $text = preg_replace('~(\R){2,}~', "\n\n", $text);
+        $text = preg_replace('~(\R){2,}~u', "\n\n", $text);
 
         // Decode HTML entities back to plain text
         return trim(Convert::xml2raw($text));

tests/php/ORM/DBHTMLTextTest.php

@@ -265,6 +265,10 @@ class DBHTMLTextTest extends SapphireTest
             [
                 '<p>Collapses</p><p></p><p>Excessive<br/><br /><br>Newlines</p>',
                 "Collapses\n\nExcessive\n\nNewlines",
+            ],
+            'Unicode character that could be confused for a line break' =>[
+                '充美好实的一天',
+                '充美好实的一天'
             ]
         ];
     }