bug in numeric_power() function

I expected 0 ^ 123.3 to be 0, but it reported error as follows

postgres=# select 0 ^ 123.3;
ERROR:  cannot take logarithm of zero

I find that there is a bug in numeric_power() function
the function caculates a ^ b based on the algorithm e ^ (lna * b)
as you see, ln0 is not valid