Consider a piece of code like this:
var $root = $("#a");
var $child = $(".b");
var $el = $root.find( $child );
This will give a Uncaught Error: SYNTAX_ERR: DOM Exception 12 because of a faulty use of document.querySelectorAll that only accepts strings or NodeLists, not Zepto objects.
Uncaught Error: SYNTAX_ERR: DOM Exception 12
jQuery's find has been accepting jQuery objects since 1.6 (link), so many people might expect this functionality to be in Zepto as well (i did at least :).
I've made a JS Bin here: http://jsbin.com/ijoqup/1/edit
Cool, thanks for fixing this!
jQuery compat: `find`, `closest` accept element args