Description of problem:

If current platform has no defined flavors, check will return a status code CRITICAL with this message "Unable to contact nova API."

In python script we can note this : 
    def flavors_list():
        try:
            return list(client.flavors.list())
        except Exception as ex:
            utils.critical(str(ex))

    elapsed, flavors = utils.timeit(flavors_list)
    if not flavors:
        utils.critical("Unable to contact nova API.")

Script check a list of flavors and if not it will return a CRITICAL error.

But the script doesn't check if API status is OK : we can have no flavors in our environment and when trying to contact flavors API it returns an ERROR

Version-Release number of selected component (if applicable):


How reproducible:
Always


Steps to Reproduce:
1. Run script when there are no flavors

Actual results:
status code CRITICAL with this message "Unable to contact nova API."

Expected results:
No error

Additional info: