Summary

If a users' username contains a space, no one can access that user's personal repositories including the user.

How to Replicate

1. In Bitbucket Server 4.4.1, create a user with a space in the username. test user
2. Fork a repository to the users' personal project.

Results: You can access the users' repository and the personal project page is visible to the user.

1. Upgrade Bitbucket Server from 4.4.1 to 4.9.1
2. Attempt access to the personal repository or project page for user test user

Results: You receive a 404 error stating that - "No project with key '~test%20user' exists."