Can not use a name of "ALL" for group ?

In our local GitLab, We were using a name of "ALL" for a group, but when I update a GitLab to Community 10.1.0, the name of the group automatically replaced to "ALL0". (Sorry but I don't remember the old version number.) So, a repository in the "ALL" group cannot access from GitLab. The original git repository is still there.

• Is the phenomenon correct?
• Is the current version cannot use a name of "ALL" for group?
• Is there have any documentation about reserved word for group?