I try to get HHVM run in Repo Authoritative mode without php source available. All files are compiled successfully and the server runs. But as soon as the source files are removed the server responds with 404. It seems that HHVM checks if the requested file exists on the disk and responds with 404 if not. The same behavior is shown in fastcgi and proxygen mode.
I am looking for the switch to turn off file existence check but havn't found the corresponding settings in the docs: https://docs.hhvm.com/hhvm/configuration/INI-settings