### Summary Existing subgroup paths are preventing users adopting the same path for their username. ### Steps to reproduce - Create a new root group (GroupA) - Create a subgroup within that group (GroupA/SubGroupA) - Attempt to change username to the path of above subgroup (SubGroupA) ### Example Project I created the following subgroup: - https://gitlab.com/groups/issue-reproduce/random-namespace-i-want This is currently preventing username change to `random-namespace-i-want`. [`random-namespace-i-want`](https://gitlab.com/random-namespace-i-want) is available. Root level group creation is not affected. `random-namespace-i-want` will be accepted as the path for a root-level group ### What is the current *bug* behavior? SubGroup paths are currently preventing users from adopting those usernames ### What is the expected *correct* behavior? Only existing namespaces at the root level should block username changes. Root level group creation is not affected. ### Output of checks This bug happens on GitLab.com #### Results of GitLab environment info gitlab-ce~3293941 v9.4.3 #### Results of GitLab application Check gitlab-ce~3293941 v9.4.3 ### Possible fixes Change appears to be prevented by the following validation: - https://gitlab.com/gitlab-org/gitlab-ce/blob/5388f5ee13c61eb9d686c9c21c027e603bc222b6/app/models/user.rb#L484