tests ~ (sub-crate/factor) fix divisor(0,0) test of factor::numeric::gcd() with early value check and return (fixes #1587)

src/uu/factor/src/numeric/gcd.rs

@@ -75,6 +75,7 @@ mod tests {
         fn divisor(a: u64, b: u64) -> bool {
             // Test that gcd(a, b) divides a and b
             let g = gcd(a, b);
+            if g == 0 { return a == 0 && b == 0; }
             a % g == 0 && b % g == 0
         }