In general the dividing line between hair lengths is pretty gray. There has been at least one thread about this, but in the end I don't believe it went anywhere. The problem is how people define their hair length. Some people for the most part only have 2 divisions for female hair, while others have 3 or even 4 divisions of hair length.
For me I wouldn't consider this either short hair or long hair.
The only hair length that has a length definition is very_long_hair.