Quality control in open source development

[Dave]

With the open source licenses that allow redistribution of modified
code, how do you keep someone unaffiliated with the Python community
from creating his or her own version of python, and declaring it to be
Python 2.6, or maybe Python 2.7 without any approval of anyone at the
PSF? Maybe their code is terrible, and not even compatible with the
rest of Python! How can the PSF, for example, maintain the quality and
coheren of new code contributed to be part of Python, or derivative
works that claim to be some future version of Python? If licensees can
redisribute as they like, isn't this a huge problem? Is this dealt
with be restricting use of the Python trademarks?  Just curious..