rename: fix opening new windows with &shellslash (Windows)
rename: fix opening new windows with &shellslash (Windows)

Ref: https://github.com/davidhalter/jedi-vim/pull/364#issuecomment-98418501

jmartiuk5/jedi-vim,aliev/jedi-vim,wilywampa/jedi-vim,maxamillion/jedi-vim,pze/jedi-vim,itchyny/jedi-vim,clavery/jedi-vim,FBruynbroeck/jedi-vim,davidhalter/jedi-vim,genzj/jedi-vim