In what circumstances will an action be remanded in a different court?

In Thomas v. Great N. Ry. Co., 147 F. 83 (9th Cir.1906), after removal from state court, the plaintiff moved to have the action remanded. After the district court denied his motion and granted a demurrer for one of the defendants, the plaintiff voluntarily amended the complaint and made the appellee the sole defendant. The appellee argued that by amending his complaint, the plaintiff submitted to the jurisdiction of the court and could no longer contend that the action was not removable. Id. at 86. This court stated that the only question was