Also present in 0.6.4:
If two incompatible races have sex (and neither has the breeder trait), the text says "[name] could get pregnant from it". After a bit of digging, I think the issue is in globals.gd:
if mother.has_status('breeder') or father.has_status('breeder'):
result.value = true
result.compatible = true
else:
result.value = false
result.breeder = false
That last line should probably be "result.compatible = false".
(The fact that "value" is false means that the pregnancy doesn't actually occur--it's just that the wrong message is generated.)