In a cramped roundhouse sometimes just the loco was shoved headfirst in the stall, being repaired, as the tender would hang out, impeding traffic ... a battery powered pusher slug was oftentimes used to shift locos about.
A roundhouse was usually not for storage purposes, but served as protection from the elements to maintenance crews and their equipment.
A steam loco, without it's tender, could operate for a short distance, being filled with water, and a bed of hot coals