[6.13.z] Setting sanity hostname attr initially (#15354)

pytest_fixtures/core/xdist.py

@@ -14,6 +14,7 @@
 def align_to_satellite(request, worker_id, satellite_factory):
     """Attempt to align a Satellite to the current xdist worker"""
     if 'build_sanity' in request.config.option.markexpr:
+        settings.set("server.hostname", None)
         yield
         if settings.server.hostname:
             sanity_sat = Satellite(settings.server.hostname)