Hi,

I have two machines, both Windows 10, both with python 2.7.12 (bug is also reproducible with 2.7.14), one of them has the Fall creator update (-> version 1709) and one doesn't (->version 1607). 

When I execute the checkout on some executable that is available on both machines, I get different behaviours: One the one without the fall creator update I get the output of that executable as expected as the return value. One the machine with the update I see a new command line window popping up, the executable runs through, and the return value of check_output is an empty string.

I'll use it like follow:

f = subprocess.check_output(['svn.exe', '--help'])