Leaves placed by the player or with the /fill command will decay after a nearby block is updated. Before 1.5.0, blocks placed by command blocks and the player would not decay even if there wasn't a wood block nearby. I only tested this with oak and jungle leaves in creative mode, if it matters.
Cleaning up old tickets: This ticket has not been updated recently (~7 months+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue and is affecting the most recent versions, then please comment, or create a new ticket following the Issue Guidelines.
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