diff -r c0a6c19690ff -r 75979c8d4572 mercurial/subrepo.py
--- a/mercurial/subrepo.py	Thu Oct 12 19:20:04 2017 -0700
+++ b/mercurial/subrepo.py	Thu Oct 12 23:30:46 2017 -0700
@@ -1347,7 +1347,7 @@
             if e.errno != errno.ENOENT:
                 raise error.Abort(genericerror % (
                     self._path, encoding.strtolocal(e.strerror)))
-            elif pycompat.osname == 'nt':
+            elif pycompat.iswindows:
                 try:
                     self._gitexecutable = 'git.cmd'
                     out, err = self._gitnodir(['--version'])