Bertrand Jomin found a bug when the Nagios plugin check_esxi_hardware was used in combination with IBM Blade Center HS21 and HS22 where the serial number doesn't contain a dot or doesn't exist. This fact broke the plugin at the point of executing and would not continue.

The error message would look like this:

 Traceback (most recent call last):
  File "./check_esxi_hardware.py", line 661, in ?
    SerialNumber = SerialNumber.split('.')[1]
AttributeError: 'NoneType' object has no attribute 'split'

This bug has now been fixed thanks to Bertrand's contribution. Merci!