azylman/optimus — pull request #6 by nathanleiby (2014-09-05 23:08:23+00:00)
Title: transforms: fieldmap shouldnt map nil values when passed nonexisting headers

see transforms_test `Fieldmap-IgnoreInvalidMap` for an example of the behavior after adding the modification

@azylman your thoughts on this change? (and additional tests to clarify the behaviors of fieldmap)