pip版本低无法升级问题
最近项目需要，在研究rk1808的开发环境，搭建环境的时候遇到了pip版本低无法安装好多软件，异常如下：
sudo pip install --upgrade pip
The directory '/home/roc/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/roc/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Exception:
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/pip/basecommand.py", line 209, in main
status = self.run(options, args)
File "/usr/lib/python2.7/dist-packages/pip/commands/install.py", line 317, in run
requirement_set.prepare_files(finder)
File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 360, in prepare_files
ignore_dependencies=self.ignore_dependencies))
File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 448, in _prepare_file
req_to_install, finder)
File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 397, in _check_skip_installed
finder.find_requirement(req_to_install, self.upgrade)
File "/usr/lib/python2.7/dist-packages/pip/index.py", line 442, in find_requirement
all_candidates = self.find_all_candidates(req.name)
File "/usr/lib/python2.7/dist-packages/pip/index.py", line 400, in find_all_candidates
for page in self._get_pages(url_locations, project_name):
File "/usr/lib/python2.7/dist-packages/pip/index.py", line 545, in _get_pages
page = self._get_page(location)
File "/usr/lib/python2.7/dist-packages/pip/index.py", line 648, in _get_page
return HTMLPage.get_page(link, session=self.session)
File "/usr/lib/python2.7/dist-packages/pip/index.py", line 760, in get_page
resp.raise_for_status()
File "/usr/share/python-wheels/requests-2.9.1-py2.py3-none-any.whl/requests/models.py", line 840, in raise_for_status
raise HTTPError(http_error_msg, response=self)
HTTPError: 404 Client Error: Not Found for url: http://repo.rock-chips.com/pypi/simple/pip/
You are using pip version 8.1.1, however version 21.0 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
陷入死循环中，异常提示使用pip install --upgrade pip即可解决该问题，但是使用pip升级时依然会检查版本。
后来怀疑是ubuntu安装源的问题，切换阿里源/清华源都无法解决。百度出来的解决方案是手动安装
wget https://bootstrap.pypa.io/get-pip.py
sudo python3 get-pip.py
结果：
sudo python3 get-pip.py --force-reinstall
File "get-pip.py", line 1
--2021-01-27 16:20:41-- https://bootstrap.pypa.io/get-pip.py
^
SyntaxError: invalid token
当时快崩溃，后来忽然留意到rknn配置环境时新建过pip的conf文件，
/etc/pip.conf
[global]extra-index-url = http://repo.rock-chips.com/pypi/simpletrusted-host = repo.rock-chips.com
然后查看了下pip下载的原来pkg-resoures中还有没有完全同步的资源
修改如下:
[global]
#index-url=http://mirrors.aliyun.com/pypi/simple/
index-url = https://pypi.python.org/simple/[install]
#trusted-host=mirrors.aliyun.com
trusted-host=pypi.python.org
将pip的conf中修改源即可，或者直接删除conf文件，重新使用升级命令后升级成功
修改后：
sudo pip install --upgrade pip
The directory '/home/roc/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/roc/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting pip
Downloading https://files.pythonhosted.org/packages/9e/24/bc928987f35dd0167f21b13a1777c21b9c5917c9894cff93f1c1a6cb8f3b/pip-21.0.tar.gz (1.5MB)
100% |████████████████████████████████| 1.6MB 28kB/s
Installing collected packages: pip
Found existing installation: pip 8.1.1
Not uninstalling pip at /usr/lib/python2.7/dist-packages, outside environment /usr
Running setup.py install for pip ... done
Successfully installed pip-21.0