Relative units with numpy integer division raises error

[samwaseda]

It looks like an edge case, but I guess it's an error coming from pint, so I raise it here.

What obviously works

def f(x, y):
    return x / y

print(f(np.array([1]), np.array([2])))

Output: [0.5]

What raises an error

from pint import UnitRegistry

ureg = UnitRegistry()


@ureg.wraps("=A/B", ("=A", "=B"))
def f(x, y):
    return x / y

print(f(np.array([1.]) * ureg.angstrom, np.array([2.]) * ureg.second)) # This one works
print(f(np.array([1]) * ureg.angstrom, np.array([2]) * ureg.second)) # This one raises an error

Here's the error message: ValueError: Integers to negative integer powers are not allowed. It's not impossible to understand what it means, but since numpy automatically converts it to a float, I think pint should also support it.

I'm using version 0.24.4