Regression layer.json with absolute URLs due to #3133

[gberaudo]

The layer.json of my Cesium terrain server defines an array of absolute URL
templates in order to allow parallel queries to subdomains.

Before #3133, the URLs were used as-is. Now, they are scrumbled:

• URL to layer.json: https://3d.geo.admin.ch/prefix/layer.json
• URL in layer.json: //terrain3.geo.admin.ch/prefix/{z}/{x}/{y}.terrain?v={version}
• generated terrain URL: https://3d.geo.admin.ch/prefix/prefix/0/1/0.terrain?v=1.0.0

The domain is incorrect and the prefix appears twice.

[kring]

This is a pretty serious regression, so I'm marking it showstopper. I will try to work on it today.

[mramato]

Thanks @kring

[gberaudo]

Thank you @kring. Let me know if I can do something to help.