Pierre-Yves David <pierre-yves.david@fb.com> [Wed, 27 May 2015 00:52:01 -0700] rev 25321
bundle2: add debug output for part generation
The part generation process was lacking a ui object and could not produce debug
output. It seems valuable to have some debug output on this part too, especially
now that we are planning to be able to hide it in the default --debug output.