Since this distribution does not include example content, I installed the Devel module and tried to add users. This resulted in :

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '' for key 'name': INSERT INTO {users} (uid, name, mail, created, status, language, data) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6); Array ( [:db_insert_placeholder_0] => 6 [:db_insert_placeholder_1] => [:db_insert_placeholder_2] => rotethefruhu@accounting.conscious-society.org [:db_insert_placeholder_3] => 1387449878 [:db_insert_placeholder_4] => 1 [:db_insert_placeholder_5] => und [:db_insert_placeholder_6] => a:7:{s:16:"ckeditor_default";s:1:"t";s:20:"ckeditor_show_toggle";s:1:"t";s:14:"ckeditor_width";s:4:"100%";s:13:"ckeditor_lang";s:2:"en";s:18:"ckeditor_auto_lang";s:1:"t";s:7:"contact";i:1;s:17:"mimemail_textonly";i:0;} ) in drupal_write_record() (line 7166 of /home/account/public_html/includes/common.inc).

Comments

matslats’s picture

matslats CreditAttribution: matslats commented
Status: Active » Closed (won't fix)

That's because the cforge_user_presave is rewriting the username according to the profile_firsname and profile_lastname fields.
You can comment it out but I'm not going to worry about this sorry.