BUG: Polynomial([inf]) divided by a float emits RuntimeWarning: invalid value encountered in multiply

Describe the issue:

A Polynomial of order 0 and with coefficient value infinity emits a RuntimeWarning when dividing it by a float:

>>> Polynomial([np.inf]) / 2
RuntimeWarning: invalid value encountered in multiply
Polynomial([inf], domain=[-1.,  1.], window=[-1.,  1.])

The return value is correct, but it shouldn't emit a warning. Multiplication works fine:

>>> Polynomial([np.inf]) * 0.5
Polynomial([inf], domain=[-1.,  1.], window=[-1.,  1.])

A higher order polynomial with finite zero order coefficient works fine:

>>> Polynomial([1, np.inf]) / 2
Polynomial([0.5, inf], domain=[-1.,  1.], window=[-1.,  1.])

Reproduce the code example:

import numpy as np
from numpy.polynomial import Polynomial

Polynomial([np.inf]) / 2

Error message:

.../python3.9/site-packages/numpy/polynomial/polynomial.py:410: RuntimeWarning: invalid value encountered in multiply
  return c1/c2[-1], c1[:1]*0

NumPy/Python version information:

1.22.3 3.9.2 (default, Mar 4 2022, 13:52:40)
[GCC 9.3.0]

Start by reproducing the warning with the Polynomial([np.inf]) / 2 example, then inspect numpy/polynomial/polynomial.py around the reported line 410. Check the surrounding division behavior and existing polynomial tests. Done means the same expression returns Polynomial([inf]) without emitting RuntimeWarning.