AI shells can no longer push crates

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Last night I was playing AI and, over the course of several rounds on both servers, found closed crates to be completely unpushable. In one round without a QM, I tried to use a shell to push it over to the Mulebot pickup spot, but the crate wouldn't budge at all in any direction, and neither would any other crates in QM. Later, at least twice, I found a shell to be completely trapped because the roboticist left a single closed crate in front of one of the shell compartments and the shell couldn't push it at all. The change log had something about recent AI shell code changes, so I thought it might be a bug accidentally introduced as part of that.