I placed a sticky piston beside a dirt block, and a rail on top of that. Placing a redstone torch beside the piston caused it to push the block and the rail to pop off. Removing the torch, expecting it to cause the piston to contract again, caused the crash. Reloading and trying again WITHOUT the rail causes no crash. Other objects, such as torches, don't seem to cause it, only rails.
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Based on a crash report provided in this issue, I believe with high certainty that this report may be a duplicate of MC-7622. If I am wrong, please go yell at Dinnerbone.

(Why is the bot slower than me ?)

Based on statistical delay analysis between report attachments and Spam Golem's responses, I believe with high certainty that it is expressing silently that its current salary does not match its performance. If I am wrong, please do not go yell at Dinnerbone.
Oops, yes, fixed by the update to the update. Sorry about that.
Possible duplicate of MC-7622 - can you redownload the snapshot and retest, there was a "Ninja update" short after releasing the crash which fixes some issues.