Avoid fatal: bad revision HEAD in Git WebUI on empty repo

[isc-tleavitt]

This is a likely situation if you've run git init and haven't committed anything yet.

[isc-tleavitt]

@isc-pbarton this would be a nice thing to have before Summit too (just thinking about the new-user experience)

[isc-rsaptars]

Needed some clarifications:
I get this error when I initialize an empty git directory through the Configure() workflow. Is there any other workflow in which git init is used to create an empty git directory?
I have fixed the Configure() workflow by adding an empty initial commit after the directory is created.

[isc-tleavitt]

@isc-rsaptars I think that's sufficient.