Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question.
• This cannot be dealt with as a third party library.
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request.

Steps to reproduce

1. Create any kind of nested namespace,
2. Try to access the url,

10fa40a

Expected behavior

NamespaceVersioning should only pull the first namespace encountered instead of whole : delimited string

Actual behavior

Returns "Invalid version in URL path.", not even namespace versioning error.