title: "Invalid utf8mb4 character string" warnings on POINT fields when importing from a mysqldump
body: <p>I recently dumped a database as part of migrating it from an old server to a new server. Some of the tables have the <code>utf8mb4</code> character set as the default collation and as the character set for some of the fields.</p>
  
  <p>One of the tables also has a field of type POINT. When I run <code>mysqldump --default-character-set=utf8mb4 ... &gt; dump.sql</code> and then try to import <code>dump.sql</code> I get the "Invalid utf8mb4 character string" warning for any rows that have a location set in the POINT field.</p>
  
  <p>Do I need to worry about this? It looks to me like the data gets migrated correctly, but I do so dislike seeing warnings!</p>
  
  <p>EDIT: Sample code and how to reproduce. The following is the output of <code>mysqldump</code> with no special options (adding the default utfmb4 charset option didn't help), on an example table of an example database. The table has one row:</p>
  
  <pre><code>/*!40101 SET NAMES utf8mb4 */;
  /*!40103 SET TIME_ZONE='+00:00' */;       
  /*!40101 SET character_set_client = utf8mb4 */;
  
  CREATE TABLE `Items` (
    `ID` int(11) NOT NULL AUTO_INCREMENT,
    `Title` varchar(255) CHARACTER SET utf8mb4 NOT NULL,
    `LatLong` point NOT NULL,      
    PRIMARY KEY (`ID`),     
    SPATIAL KEY `LatLong` (`LatLong`)
  ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4;
  
  INSERT INTO `Items` VALUES (1,'item1','\0\0\0\0\0\0\0?4??=@\??O@?V?');
  </code></pre>
  
  <p>If you run from with mysql <code>source file.sql</code> on the file containing this SQL you get the following warnings on the insert:</p>
  
  <pre><code>Query OK, 1 row affected, 1 warning (0.00 sec)
  Warning (Code 1300): Invalid utf8mb4 character string: 'BE141E'
  </code></pre>
  
  <p>Further information:</p>
  
  <pre><code>&gt; file -i file.sql
  file.sql: application/octet-stream; charset=binary
  
  &gt; mysql --version
  mysql  Ver 14.14 Distrib 5.7.17, for Linux (i686) using  EditLine wrapper
  </code></pre>
  
  <p>Running Ubuntu 16.04 LTS</p>