jquery/api.jquery.com — pull request #344 by Timothee (2013-07-22 18:01:58+00:00)
Title: append() clones for all elements but the last one, not first

This can be tracked to this line in the code:
https://github.com/jquery/jquery/blob/master/src/manipulation.js#L42

And for `domManip`:
https://github.com/jquery/jquery/blob/master/src/manipulation.js#L233
`iNoClone` is what decides if the element is cloned or not, and this is set a bit above to `length - 1` which means it won't clone for the last one.

Can also be seen in this "pen": http://codepen.io/adrolldev/pen/zmonw