Copying then pasting a task list pastes a list item

Issue Summary

This is reproducible on Data Center: (yes) / (no)

Steps to Reproduce

1. Add a line of text to a page.
2. Add a task list on the second line.
3. Hit enter and add some more text to the third line.
4. Hit enter, creating a fourth line.
5. Use your mouse to select the task list line and copy it using your keyboard.
6. Go back to the fourth line and paste using your keyboard.

Expected Results

A copy of the copied task list should be pasted.

Actual Results

A list item is pasted instead of a task list item.

Workaround

Manually add a task list instead of copying and pasting existing ones.