Some inaccessible links exist in docs/conf.py

[shenxianpeng]

I've noticed some links in docs/conf.py that are no longer accessible:

setuptools/docs/conf.py

Line 16 in ba24375

BB='https://bitbucket.org',

setuptools/docs/conf.py

Lines 37 to 38 in ba24375

	pattern=r'BB Pull Request ?#(?P<bb_pull_request>\d+)',
	url='{BB}/pypa/setuptools/pull-request/{bb_pull_request}',

setuptools/docs/conf.py

Line 50 in ba24375

url='https://bugs.python.org/setuptools/issue{old_setuptools}',

It might be a good idea to remove these links.