依旧是python版本问题：
[root@westos1 ~]# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /usr/local/bin/python2.7 /usr/local/bin/python2.7-config /usr/local/bin/python /usr/local/lib/python2.7 /usr/include/python2.7 /usr/share/man/man1/python.1.gz
[root@westos1 ~]# vim /usr/libexec/urlgrabber-ext-down 更改成对应的即可