Fix for use with phpBB2Drupal

Issue Summary

Hi,

I'm working on my first Drupal project, and don't yet know how create patches :-/

But anyways, i'm currently importing a phpBB3 forum into drupal forum with the phpBB2Drupal module, and i'm doing som bugfixes.

When importing users, the signatures don't get into the signatures_forum table, and therefore i investigated it a little. And after some snooping around i found that if i added;

case 'insert':

in signature_forum.module on line 273 in function signature_forum_user() it now works like a charm...

/**
* Implementation of hook_user().
*/
function signature_forum_user($op, &$edit, &$account, $category = NULL) {
// Re-route the user signature to this module's signature table.
switch ($op) {
case 'insert':
case 'submit':
// Check if the signature is set in the form
// (#276349 - Signature deleted when editing profile).
if (!isset($edit['signature'])) {
break;
}

...

This is because phpBB2Drupal creates new users (insert) when importing, and the above hook is only applied if the signature is changed (submit).