emberjs/ember.js — comment on commit 9e099c1ffd0c49f9ffdb08c9c8adc9a5c2ecf0cb
File:  line 0
By wagenet:

This change means that `Ember.A` can no longer be used to convert `arguments`. It also means that we modify the original array vs. returning a new one. This seems like it could cause some unexpected behavior.