BUG: temperature units comparison

[neutrinoceros]

• unyt version: 2.9.5

Description

I would not expect Kelvin and degree Celsius to compare equal, yet this is the current result of Unit.__eq__

What I Did

import unyt as un
assert un.K != un.degC

raises AssertionError

Note that on the main branch (unyt 3.0, using NEP 18), this is breaking array comparison

import numpy as np
import unyt as un
assert all(np.isclose([1, 2, 3] * un.K, [-272.15, -271.15, -270.15] * un.degC))

I think the correct solution is to include Unit.base_offset in the comparison routine, but I'm not 100% certain.

[neutrinoceros]

FTR #408 is only part of the solution to this issue.
Another problem with np.isclose and temperature units is that the following line will raise an error for units that have a base_offset

unyt/unyt/_array_functions.py

Line 472 in 79ef518

if (bu / au).is_dimensionless:

this is probably simple enough to fix, though to avoid building a chain of co-dependent PRs, I'll wait for #410 and #408 to be resolved.