minor bug found in factor 5.2.1

[Thomas Folz-Donahue]

When I tell it to factor 1, it returns 1 as a prime factor.

address@hidden:~ ^_^]$ factor 1
1: 1

It does not exhibit this or any similar bug when asked to factor 0.

address@hidden:~ ^_^]$ factor 0
0:

This is a minor and irrelevant bug on an otherwise highly useful
program.  However, it is incorrect behavior, and makes the program
just look silly.

-tfd