Addition of a unit test that reproduce the error found

This is to protect for future erros like this.

The error is that the remote url is empty.

re #6923
Protection from empty remote url

Correct the steps of construction, first get the remote url information,
and them the local paths. Besides, protect install method to attempt
to install on an empty remote_url.

re #6923
Merge branch 'bugfix/6923_auto_update' into develop