Right now.
There are no live bearing pythons, are there? If they were moved into the Python family, then they'd be the first, or is there already?
Well... couple things, first one... Like I said, reproductive method isn't of taxonomic signifigance at that level. All reptiles technically lay eggs, it's just a question of where the eggs are incubated.
Secondly... there are a few groups which share common names but aren't exactly super-closely related.
The EMBL taxonomy database or the NCBI are both nice and reliable, making changes within a year or two (once proposed changes have been given some consideration) and keeping notes about who changed what, when, why and where their reasons were published. Just kinda throwing a plug in for websites which allow for nice easy access to decent taxonomic information.
Superfamily Boidea is divided into a number of families.
Aniliidae (Pipe Snakes)
Anomochilidae (Dwarf Pipe Snakes)
Boidae (Boas and Pythons)
Bolyeridae (Round Island Boas)
Cylindrophiidae (Asian Pipe Snakes)
Loxocemidae (Mexican Burrowing Pythons)
Tropidophiidae/Ungaliophiidae (Dwarf Boas)
Uropeltidae (Shield-tail Snakes)
Xenopeltidae (Sunbeam Snakes)
Boidae contains Boas, Pythons and Sand boas but there are animals not too closely related which have common names of Boa or Python (Round Island boas or mexican burrowing pythons for example- which are completely independant of the "Boa versus Python" debate). So a typical python is more closely related to a typical boa than a round island boa is... Really just adding that because there's some common name confusion at times and it illustrates the importance of taxonomy, if it's also understood that it's a highly subjective science which is sometimes driven more by the egos of the taxonomists than any legitimate study or debate.
So... Boidae. Contains the subfamilies Boinae, Pythoninae and Erycinae. Some taxonomists and some older works on taxonomy will designate Pythonidae as a seperate family but as of right now it's generally accepted that the distinction belongs on a subfamilial level.
Now, the difference between Pythons and Boas (including sand boas) is the prescence or abscence of a Coronoid bone. Sort of. It's really more the development of the coronoid bone, since it's kind of sort of present in a vestigial state in both groups... The coronoid bone is found only in more primitive snake species and the majority of snakes have lost it as they evolved... it's a bone in the jaw which makes the jaw more ridgid. Means a stronger jaw but also one which is less flexible, making it tougher to injest larger prey items... Anyway, Boas have a well developed coronoid bone, pythons have barely got a remnant of one (to the point where it borders on entirely absent and is usually reffered to as such unless someone is really getting into specifics about it).
So calabaria, having a well developed and obvious coronoid bone, is a boa. They can drop all the eggs they want to (although offhand I don't *think* there have been any CBB animals produced, just eggs dropped from females collected while gravid... may be wrong there but it was true as of a couple years ago anyway. Probably. Maybe.) but it doesn't make 'em a python.
Thereare no Pythoninae which are oviviparous.
There aren't any other species or groups that I know of offhand with the common name "Python" which are either... Since Loxocemidae (Mexican burrowing "pythons") are also oviparous... But since it's a frequenrly related discussion and there are egg laying boas, both Boinae and representatives of other familial groups with the common name, it's kind of important to make the distinction.
So there are no live bearing pythons but the fact that an animal lays externally incubating eggs isn't used in determining it's status as a python or a boa.
