In the issue #316 we discussed possibility to use spaces in project name and the explanation is that it is not possible because the same name is used for repository names and other stuff.

However, the REST API allows to create project with spaces in the name, and then, the project causes problems when trying to edit it's properties on the website.

So, either the REST API should not allow to create project with spaces in name or the website code should be updated to support it.