" I doubt that this comes from a student handbook!"
Well I guess that they put some lie in my international student handbook, I might as well throw it away. Anyway, depending on the reason you are staying abroad, you will need a new I-20. You want need a new I20 if your school keep your Sevis form valide while you are studying abroad. Sorry for the incorrect information about studying abroad and the I-20, my handbook did not go into the details so I looked it up.
"Students who are enrolled in schools in the United States may take a break from studies and return home for a semester or more, with their school’s permission. An F-1 student returning to the United States from a temporary absence of five months or less may be readmitted for study upon presentation of a valid I-20. However, when a student has been out of the country for more than five months (and is not pursuing studies overseas) the student’s F-1 or M-1 visa is considered to be invalid, even though the actual visa may not have expired. In this situation a new visa is required for re-entry into the United States. Students who have the approval of their schools to take an extended break from study must have their SEVIS record terminated for Authorized Withdrawal. When the student is ready to resume study, the school will issue the student a new initial Form I-20 with a new SEVIS number. These students must pay the SEVIS I-901 fee."
Student Visa Validity Following a Break in Studies
I hope that you all get to do whatever you want after or before graduation