Respect the environment variable "force_host_os" to override host detection
As of LbEnvBootstrap!10 (merged) we can override the host OS detection in LbEnv entry script, but then the user is faced by lb-run not allowing the proposed platform.
As of LbEnvBootstrap!10 (merged) we can override the host OS detection in LbEnv entry script, but then the user is faced by lb-run not allowing the proposed platform.