Please have a look at https://en.wikipedia.org?oldid=646252340#User:A_Texas_Historian : I've global-renamed a user account and tried to move his user (sub)pages to his new name. Unfortunately, the user himself manually moved his subpages earlier leaving a redirect behind on its former place. As soon as I moved the redirect, the new subpage was overriden by the redirect which caused a double-redirect on the former place (see e.g. https://en.wikipedia.org/w/index.php?title=User_talk:A_Texas_Historian/Archive_1&redirect=no). This move resulted in an onwiki loss of the entire history of the earlier moved subpage. According to hoo, the history can still be found in the database and manually be restored. But obviously, it should not get lost onwiki only due to a global rename move. This bug may also affect all user subpages which are targets of a global rename move.