Whenever any certificated employee of any school district who, at the time of his or her resignation, was classified as permanent, is reemployed within 39 months after his or her last day of paid service, the governing board of the district shall, disregarding the break in service, classify him or her as, and restore to him or her all of the rights, benefits and burdens of, a permanent employee, except as otherwise provided in this code. However, time spent in active military service, as defined in Section 44800, subsequent to the last day of paid service shall not count as part of the aforesaid 39-month period.