Comment 2 for bug 1862668

Kristine may want to examine the algorithm being used.
Python2 uses integer math, but python3 uses floating point.

Example:

This unit test:
https://opendev.org/starlingx/config/src/branch/master/sysinv/sysinv/sysinv/sysinv/tests/api/test_controller_fs.py#L411

Python2 the result is:
Total target growth size 9 GiB for database (doubled for upgrades), platform, scratch, backup and extension exceeds growth limit of 0 GiB.

Python3, the result is:
Total target growth size 8.0 GiB for database (doubled for upgrades), platform, scratch, backup and extension exceeds growth limit of 1.540139

It is trivial to make the python3 work like python2, but the python2 formula should be re-examined, in case it is not accurate.