Upon the trial of the warrant on appeal the court may, upon its own motion or upon the request either of the attorney for the prosecution or for the accused, amend the form of the warrant in any respect in which it appears to be defective. But when the warrant is so defective in form that it does not substantially appear from the same what is the offense with which the accused is charged, or even when it is not so seriously defective, the judge of the court having examined on oath the original complainant, if there be one, or if he sees good reason to believe that an offense has been committed, then without examination of witnesses, may issue under his own hand his warrant reciting the offense and requiring the defendant in the original warrant to be arrested and brought before him. Upon the arrest of the defendant on the new warrant and his production or appearance in court the trial shall proceed upon the new warrant. When there is an amendment of the original warrant the trial shall proceed on the amended warrant. But whether the warrant is amended or a new warrant is issued, the court before proceeding to trial on the same may grant a continuance to the prosecution or to the defendant upon such terms as to costs as may be proper under the circumstances of the case; provided, however, that if the warrant be amended or if a new warrant be issued after any evidence has been heard, the accused shall be entitled to a continuance as a matter of right. When a warrant is amended or a new warrant is issued the costs already accrued shall be taxed against the defendant, if he is ultimately convicted, as a part of the costs arising under the new or amended warrant.