I've been experimenting with the /fill and /clone commands to make teleportation based vehicles, like the one in this Reddit thread: http://www.reddit.com/r/Minecraft/comments/1w1re0/warp_ship/
I've noticed that if I use /fill with mode 'replace', the command blocks in a selected region do not change to the selected block. /fill 'destroy' works, but of course that leaves loose blocks all over the place. As you can see in the link, I am not the only person to experience this.
Steps to reproduce:
1. Create a selection that a command block can fill
2. Place another command block in the region
3. Fill the region in 'replace' mode with air
4. Notice that the command block remains
Linked issues
Attachments
Comments
/filling a redstone block in the region, turning it to air
Command block will not /fill
Example of the command