bcolz has been created by Francesc Alted, so he must be responsible for most of the bugs in the beast.
Valentin Haenel did an impressive work working as a maintainer and release manager for long time.
Francesc Elies contributed many improvements to bcolz.
Gabi Davar contributed a much better setup.py.
Also, most of the Python 3 support is a back porting of the work that Mark Wiebe did for the BLZ package.
Matthew Rocklin and Phillip Cloud contributed conda and binstar recipes.
Alistair Miles contributed the conda-forge recipe and other improvements.
Many other contributed bug fixes and new features.