alanclarke/najax — pull request #2 by rhildred (2013-12-26 04:09:53+00:00)
Title: initialize headers to {} if we need to copy some. 

Not sure if this is a bug in underscore, but without this I got:

najax/node_modules/underscore/underscore.js:822
obj[prop] = source[prop];
^
TypeError: Cannot set property '...' of undefined