Noticed that via it is not possible to rename the own account using https://meta.wikimedia.org/wiki/Special:GlobalRenameUser but it seems to be possible via Special:GlobalRenameQueue/open it is.
- (User rename log); 14:55 . . Global rename script (Talk) renamed user TrashUser (0 edits) to STrashAccount
- (Global rename log); 14:55 . . STrashAccount (Talk | contribs) globally renamed TrashUser to STrashAccount
Just for the record. Not sure if worth fixing.