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('.')
AttributeError: 'NoneType' object has no attribute 'split'
This bug has now been fixed thanks to Bertrand's contribution. Merci!