Call sem.release(5) would have the same effect as:

with lock:
    for i in range(5):
         sem.release()

The use case is when a single semaphore is holding up multiple threads and needs to release them all.  According to "The Little Book of Semaphores <http://greenteapress.com/semaphores/>", this is a common design pattern.

Basic patch attached.  If the proposal meets with acceptance, will add tests and a doc update.