google/closure-library — pull request #334 by nicks (2014-08-19 16:25:34+00:00)
Title: Add an addFinally method to Deferreds

Add an addFinally method to Deferreds, to do cleanup without inadvertently disrupting uncaught error propagation.

We've found this useful, because this is how people were using addBoth in practice (for 'finally'-like cleanup jobs)