Couldn't find index page for 'singledispatch' (maybe misspelled?)

报如下错：

Installed /usr/local/python27/lib/python2.7/site-packages/rpy2-2.8.5-py2.7-linux-x86_64.egg
Processing dependencies for rpy2==2.8.5
Searching for singledispatch
Reading http://pypi.python.org/simple/singledispatch/
Download error: unknown url type: https -- Some packages may not be found!
Couldn't find index page for 'singledispatch' (maybe misspelled?)
Scanning index of all packages (this may take a while)
Reading http://pypi.python.org/simple/
Download error: unknown url type: https -- Some packages may not be found!
No local packages or download links found for singledispatch
Best match: None
Traceback (most recent call last):
  File "setup.py", line 414, in <module>
    'rpy2': ['doc/source/rpy2_logo.png', ]}
  File "/usr/local/python27/lib/python2.7/distutils/core.py", line 151, in setup
    dist.run_commands()
  File "/usr/local/python27/lib/python2.7/distutils/dist.py", line 953, in run_commands
    self.run_command(cmd)
  File "/usr/local/python27/lib/python2.7/distutils/dist.py", line 972, in run_command
    cmd_obj.run()
  File "build/bdist.linux-x86_64/egg/setuptools/command/install.py", line 76, in run
  File "build/bdist.linux-x86_64/egg/setuptools/command/install.py", line 104, in do_egg_install
  File "build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 211, in run
  File "build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 427, in easy_install
  File "build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 478, in install_item
  File "build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 519, in process_distribution
  File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 563, in resolve
  File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 799, in best_match
  File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 811, in obtain
  File "build/bdist.linux-x86_64/egg/setuptools/command/easy_install.py", line 434, in easy_install
  File "build/bdist.linux-x86_64/egg/setuptools/package_index.py", line 475, in fetch_distribution
AttributeError: 'NoneType' object has no attribute 'clone'

解决办法：

到以下链接https://pypi.python.org/simple/singledispatch/下载singledispatch-3.4.0.1.tar.gz