segmentio/analytics.js — pull request #287 by philfreo (2013-10-02 04:12:33+00:00)
Title: Bugfix by cloning arguments before each invoke

I had Mixpanel and Customer.io

But due to this bug Customer.io was never receiving the `email` address, since the Mixpanel integration clobbered the original `email` trait when it converted it to `$email`.

Fix + test

You may also want to add a higher level functionality test (rather than just the raw mechanics of `_invoke`)