Error of math domain could be seen if tracekback occurs for manila_share_extend test

[Anandprakash]

Environment- RHOSP13
protocol enabled - netapp
manila is configured
openstack-tempest-18.0.0-2.el7ost.noarch

When I run the test manila_share_extend,I could see following traceback:

    Trying to fetch the list of tempest tests via command:
    Test list prepared successfully!
    Plugin selected: manila
    API list selected: manila_share_extend
    Traceback (most recent call last):
      File "/bin/ostestr", line 10, in <module>
        sys.exit(main())
      File "/usr/lib/python2.7/site-packages/os_testr/ostestr.py", line 263, in main
        exit(ostestr(sys.argv[1:]))
      File "/usr/lib/python2.7/site-packages/os_testr/ostestr.py", line 259, in ostestr
        return _select_and_call_runner(opts, regex, others)
      File "/usr/lib/python2.7/site-packages/os_testr/ostestr.py", line 212, in _select_and_call_runner
        black_regex=opts.black_regex)
      File "/usr/lib/python2.7/site-packages/os_testr/ostestr.py", line 171, in call_testr
        commands.slowest_command()
      File "/usr/lib/python2.7/site-packages/stestr/commands/slowest.py", line 93, in slowest
        known_times = format_times(known_times)
      File "/usr/lib/python2.7/site-packages/stestr/commands/slowest.py", line 42, in format_times
        math.log10(times[0][1])) + 1

[Attila Fazekas (afazekas)]

The bug was in stestr and it is fixed:
https://github.com/mtreinish/stestr/commit/09cc5d2a41ec04b808770ef4b41f1087b5c7e8cb#diff-c6629310ffaaf8e44b83fea266c89480