Itseez/opencv — pull request #1140 by StevenPuttemans (2013-07-17 13:46:43+00:00)
Title: Added Bugfix 1873: returning _descriptors parameter

Like mentioned in the bugfix, the _descriptor containing the keypoint descriptors in the bagofwords.cpp approach can be returned with this extra statement.

http://code.opencv.org/issues/1873