use pathlib.Path instead of os.path.isfile

Author: gcmarx

git/util.py

@@ -464,6 +464,12 @@ def _is_cygwin_git(git_executable: str) -> bool:
 
             # Just a name given, not a real path.
             uname_cmd = osp.join(git_dir, "uname")
+
+            if not (pathlib.Path(uname_cmd).exists() and os.access(uname_cmd, os.X_OK)):
+                _logger.debug(f"Failed checking if running in CYGWIN: {uname_cmd} is not an executable")
+                _is_cygwin_cache[git_executable] = is_cygwin
+                return is_cygwin
+
             process = subprocess.Popen([uname_cmd], stdout=subprocess.PIPE, universal_newlines=True)
             uname_out, _ = process.communicate()
             # retcode = process.poll()