So, I want to keep this from happening:
To that end, I like to park my bicycle rear-wheel first, which was discussed in answers to this question, where I'm taking the images from. Since almost everywhere I need to leave my bike the stands tend to be of the variety you stick your front wheel into (image below), I like to park my bike rear-wheel first and lock the frame to the rack. Most of the time, the rack has space for the rear derailleur either inside or outside the rack.
This brings me to my question: Should the rear derailleur be between the tines of the rack, or should it be outside the structure? In other words, which sprocket should I have the chain on when it goes to the rack? For purposes of this question, please assume I don't have a kickstand.