convert2rhel fails with a backtrace in _bad_kernel_package_signature() constantly

Issue

• When executing convert2rhel on a CentOS 7 system, the conversion always fails with the following traceback

  Traceback: Traceback (most recent call last):
    File "/usr/lib/python2.7/site-packages/convert2rhel/actions/__init__.py", line 393, in run
      action.run()
    File "/usr/lib/python2.7/site-packages/convert2rhel/actions/system_checks/rhel_compatible_kernel.py", line 49, in run 
      _bad_kernel_package_signature(system_info.booted_kernel),
    File "/usr/lib/python2.7/site-packages/convert2rhel/actions/system_checks/rhel_compatible_kernel.py", line 119, in _bad_kernel_package_signature
      kernel_pkg_obj = get_installed_pkg_objects(name, version, release, arch)[0]
  IndexError: list index out of range