Command blocks can be placed down by dispensers, and I expected it to do just that.
What actually happened was the dispenser dropping the block as an item, not as an actual block.
How to trigger it:
1. Create an NBT command block
2. Place it in a dispenser
3. Activate it
I have made sure it is not a dropper. Bug or intended?
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-80671. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.