subscription-manager, rhn_register, sosreport commands fail due to 'Error: No module named ...'

Issue

Subscription-manager commands return:

[root@system ~]# subscription-manager register
Unable to find Subscription Manager module.
Error: No module named M2Crypto

[root@system]# rhn_register
Traceback (most recent call last):
...
  File "/usr/share/rhn/up2date_client/up2dateErrors.py", line 14, in 
    import OpenSSL
ImportError: No module named OpenSSL