some incorrect version specification return current version instead of error

[vboyce]

I think something is a little wonky in how dataset version specifications are parsed. Some incorrect version specifications like "v6" will return the current version instead of an error.

Here's the behavior I've observed:

#returns current version (7_3)
redivis$user("mcfrank")$dataset("refbank:2zy7", version="v6")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="8")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="v")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="vv1._")$get()

# returns appropriate prior version
redivis$user("mcfrank")$dataset("refbank:2zy7", version="6.0")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="7_2")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="v7_2")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="v7.2")$get()

# errors appropriately
redivis$user("mcfrank")$dataset("refbank:2zy7", version="v8.0")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="foo")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="6.1")$get()
redivis$user("mcfrank")$dataset("refbank:2zy7", version="7.3.1")$get()