Running :sort on line selection includes extra line

[sophiebits]

If I have a file

d
c
b
a

and I select the middle two lines using V (visual line selection) then run :sort (really, :'<,'>sort), I end up with a file that reads "d a b c" and a resulting selection of three lines long. It should output "d b c a" with still two lines selected.

Atom: 1.21.1
Electron: 1.6.15
Chrome: 56.0.2924.87
Node: 7.4.0
ex-mode: 0.18.0
vim-mode-plus: 1.13.0
OS: macOS Sierra 10.12.6

(mistakenly opened as t9md/atom-vim-mode-plus#935)

[caspertsui]

I got the same issue but only one extra line from bottom this means it sorts "c b a" when I selected "c b" for sorting.