title: FOS User bundle : Column 'salt' cannot be null during change password
body: <p>Previously, the app was in PHP7.0, SF 3.1, and FOS/UserBundle 2.0.</p>
  
  <p>After the migration to PHP7.2 with SF 3.4 and FOS/UserBundle 2.1, during a change password, I encounter that:</p>
  
  <pre><code>$ bin/console fos:user:change-password toto pass1234
  
  SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'salt' cannot be null" ["exception" =&gt; Doctrine\DBAL\Exception\NotNullConstraintViolationException { …},"command" =&gt; "fos:user:change-password toto pass1234","message" =&gt; """  An exception occurred while executing 'UPDATE fos_user SET salt = ?, password = ? WHERE id = ?' with params [null, "$2y$13$LOb\/************************************wof0QpTGGpzGi", 2]:\n  \n  SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'salt' cannot be null  """] []
  
  In AbstractMySQLDriver.php line 123:
  
    An exception occurred while executing 'UPDATE fos_user SET salt = ?, password = ? WHERE id = ?' with params [null, "$2y$13$LOb\/************************************wof0QpTGGpzGi", 2]:                                            
  
    SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'salt' cannot be null                                                                      
  
  
  In PDOStatement.php line 144:
  
    SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'salt' cannot be null                                                                      
  
  
  In PDOStatement.php line 142:
  
    SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'salt' cannot be null                                                                      
  
  
  fos:user:change-password [-h|--help] [-q|--quiet] [-v|vv|vvv|--verbose] [-V|--version] [--ansi] [--no-ansi] [-n|--no-interaction] [-e|--env ENV] [--no-debug] [--] &lt;command&gt; &lt;username&gt; &lt;password&gt;
  </code></pre>