message: Allow to substitute executed program in `ProcessBuilder`
diff: @@ -33,6 +33,11 @@ impl fmt::Display for ProcessBuilder {
  }
  impl ProcessBuilder {
  + pub fn program<T: AsRef<OsStr>>(&mut self, program: T) -> &mut ProcessBuilder {
  + self.program = program.as_ref().to_os_string();
  + self
  + }
  +
  pub fn arg<T: AsRef<OsStr>>(&mut self, arg: T) -> &mut ProcessBuilder {
  self.args.push(arg.as_ref().to_os_string());
  self
  