To be a (good) software developer you need to be at least a little bit honest with yourself (can't learn from mistakes if you can't acknowledge you made a mistake, etc.), you need to be curious, you need to be willing to observe and learn and you need to be able to put effort including in things that may not necessarily have immediate payoff.
All of which, I think, correlate with being a good person. Does not mean you will be a good person, it just means there is higher chance.
And, in retrospective, all good developers I have ever got chance to know a little better were nice, good people (at least to me). Which is not true for general developer population (which is to say I also got to know a lot of shitty people which were never good developers).