It's rare but there may be a few cases of pythons producing eggs by them selves.

There was an article last year about a female Burmese python in Europe that kept laying eggs without a male. They where surprised to find that some where fertile and genetic testing indicated they where clones of the mother. However, last I heard they hadn’t actually tried to hatch any.

A vet who posts on kingsnake reports having a female ball produce fertile eggs after being in isolation for years. This was some time ago and they aren’t still available for testing to see if they are pathogenic or just retained sperm.

I got an e-mail last year from someone who's son's pet ball python laid eggs after years of not being with another snake. They where having trouble finding someone to incubate them and I tried to help them find someone local but even the local zoo just assumed they would be infertile and didn't want to try. I checked back with the mom this year and she reports that they where infertile (still, I would like to know that they got a good chance at incubation in case they just died).

I bought a ball from a guy who has a well documented (because of the morph types involved) case where a female bred different males in two consecutive years but produced babies from the first year’s male both years.