安装keras时出错，求帮忙

C:\Users\Administrator>pip install keras -U --pre
Collecting keras
Exception:
Traceback (most recent call last):
File "D:\Anaconda\lib\site-packages\pip\basecommand.py", line 215, in main
status = self.run(options, args)
File "D:\Anaconda\lib\site-packages\pip\commands\install.py", line 335, in run
wb.build(autobuilding=True)
File "D:\Anaconda\lib\site-packages\pip\wheel.py", line 749, in build
self.requirement_set.prepare_files(self.finder)
File "D:\Anaconda\lib\site-packages\pip\req\req_set.py", line 380, in prepare_files
ignore_dependencies=self.ignore_dependencies))
File "D:\Anaconda\lib\site-packages\pip\req\req_set.py", line 554, in _prepare_file
require_hashes
File "D:\Anaconda\lib\site-packages\pip\req\req_install.py", line 278, in populate_link
self.link = finder.find_requirement(self, upgrade)
File "D:\Anaconda\lib\site-packages\pip\index.py", line 465, in find_requirement
all_candidates = self.find_all_candidates(req.name)
File "D:\Anaconda\lib\site-packages\pip\index.py", line 423, in find_all_candidates
for page in self._get_pages(url_locations, project_name):
File "D:\Anaconda\lib\site-packages\pip\index.py", line 568, in _get_pages
page = self._get_page(location)
File "D:\Anaconda\lib\site-packages\pip\index.py", line 683, in _get_page
return HTMLPage.get_page(link, session=self.session)
File "D:\Anaconda\lib\site-packages\pip\index.py", line 811, in get_page
inst = cls(resp.content, resp.url, resp.headers)
File "D:\Anaconda\lib\site-packages\pip\index.py", line 731, in __init__
namespaceHTMLElements=False,
TypeError: parse() got an unexpected keyword argument 'transport_encoding'