Notwithstanding Section 60851, if a school district determines that a pupil does not possess sufficient English language skills to be assessed pursuant to Section 60850, the district may defer the requirement that the pupil pass the high school exit examination for a period of up to 24 calendar months of enrollment in the California public school system until the pupil has completed six months of instruction in reading, writing, and comprehension in the English language. Nothing in this section shall be construed to allow any pupil to receive a diploma of graduation from high school without passing the exit examination, in English, prescribed by Section 60850.