### Factorial simplification error

I've run into an issue when running simplify on an equation containing a factorial:

```
sage: var('n')
sage: z1 = (-1)^(1/2*(n - 1))*factorial(n) == 0
sage: z2 = 0 == (-1)^(1/2*(n - 1))*factorial(n)
sage:
```~~z1.simplify_trig()
-I*n*(-1)^(1/2*n) ~~z1.simplify()
n*(-1)^(1/2*n - 1/2) != 0
sage: ~~z2.simplify_trig()
~~z2.simplify()
0 == ~~-I*(-1)^(1/2*n)*factorial(n)
~~(-1)^(1/2*n - 1/2)*factorial(n)

My best guess is when sage sends the equation down to maxima for simplification it's interpreting

```
(-1)^(1/2*(n - 1))*n! = 0
```

as

```
(-1)^(1/2*(n - 1))*n != 0
```

Any ideas on how I can work around this?