Don't update site on branches, but still see the results?

Currently, cmucl-site generates the site on any branch. This also means that any in-progress branch modifies the official site. I think this should only happen for the main branch (or some other official branch). For other branches, I want it uploaded so I can see the results, but doesn't update the official site. Any ideas on this? Will staging areas work? What about gitlab environments? -- Ray