Ticket #25709: 25709.2.diff

src/wp-includes/query.php

@@ -1986 +1986 @@
                         else
                                 $term = trim( $term, "\"' " );
 
-                        // \p{L} matches a single letter that is not a Chinese, Japanese, etc. char
-                        if ( ! $term || @preg_match( '/^\p{L}$/u', $term ) )
+                        // Avoid single A-Z.
+                        if ( ! $term || ( 1 === strlen( $term ) && preg_match( '/^[a-z]$/i', $term ) ) )
                                 continue;
 
                         if ( in_array( call_user_func( $strtolower, $term ), $stopwords, true ) )