If an employee of a school district, including a district having the merit system as outlined in Article 6 (commencing with Section 45240) of Chapter 5, employed in a position in the classified service is assigned to a position in the same district requiring certification qualifications, the employee shall retain all sick leave, vacation, and other rights and benefits accumulated by the employee at the time he or she is assigned to a position requiring certification qualifications. All seniority and permanency rights shall be secured to the employee during the period of time he or she occupies a position in the certificated service. The employee’s return to the classified service at any time shall be treated as if there had not been an interruption in his or her classified service.