语法错误：无效语法在centos6.9中安装Django时

Question

我在执行这个命令“sudo pip install django”时遇到以下错误

 Traceback (most recent call last):
 File "/usr/bin/pip", line 7, in <module>
 from pip._internal import main
 File "/usr/lib/python2.6/site-packages/pip/_internal/__init__.py", line 42, in <module>
from pip._internal import cmdoptions
File "/usr/lib/python2.6/site-packages/pip/_internal/cmdoptions.py", line 16, in <module>
from pip._internal.index import (
File "/usr/lib/python2.6/site-packages/pip/_internal/index.py", line 526
{str(c.version) for c in all_candidates},
                  ^
SyntaxError: invalid syntax

python安装的版本是python 2.7.11，使用命令python-V