I'm using Mac version sourcetree1.7.3. I've set the diff tool as "Other" and point to my vimdiff path, the Arguments is "-d $LOCAL $REMOTE". Then use the External Diff button, there is only LOCAL file but no REMOTE file. My macvim hint the REMOTE file path is /private/var/folders/m4/f_hd3wgd3xv4_7gch2r4p3h80000gn/T/HNkd6f_test.py
But there is no such file.