message: named-profiles: when -Z unstable-options not specified, don't validate --profile
  Fixes
diff: @@ -322,15 +322,23 @@ pub trait ArgMatchesExt {
  }
  if self._is_present("release") {
  + if !config.cli_unstable().unstable_options {
  + Ok(ProfileKind::Release)
  + } else {
  match specified_profile {
  None | Some(ProfileKind::Release) => Ok(ProfileKind::Release),
  _ => failure::bail!("Conflicting usage of --profile and --release"),
  }
  + }
  } else if self._is_present("debug") {
  + if !config.cli_unstable().unstable_options {
  + Ok(ProfileKind::Dev)
  + } else {
  match specified_profile {
  None | Some(ProfileKind::Dev) => Ok(ProfileKind::Dev),
  _ => failure::bail!("Conflicting usage of --profile and --debug"),
  }
  + }
  } else {
  Ok(specified_profile.unwrap_or(default))
  }
  