pycurl: libcurl link-time ssl backend (nss) is different from compile-time ssl backend (none/other)

[root@cdh-vm logs]# yum update -y
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   pycurl: libcurl link-time ssl backend (nss) is different from compile-time ssl backend (none/other)

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.7.5 (default, Aug  4 2017, 00:39:18) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]

If you cannot solve this problem yourself, please go to 
the yum faq at:
  http://yum.baseurl.org/wiki/Faq
  
How to fix:

remove existing pycurl installation

[root@cdh-vm logs]# pip uninstall pycurl
export variable with your link-time ssl backend (which is nss above)

[root@cdh-vm logs]# export PYCURL_SSL_LIBRARY=nss
[root@cdh-vm logs]# pip install pycurl