python: Fix //tools/python:pywrapper_test; use correct path to program

I typo'd the variable name when copying into my Google codebase. Name
should have been "path" instead of "cmd".

PiperOrigin-RevId: 507630790
Change-Id: I4c84b70ac0b978cbbb36bdf72177f31211456964

tools/python/pywrapper_test.py

@@ -90,7 +90,7 @@ def setup_tool(self, cmd):
     # work -- they simply fail with "Killed: 9". To workaround that, just
     # re-exec the actual binary.
     self.ScratchFile("dir/" + cmd,
-                     ["#!/bin/sh", 'exec {} "$@"'.format(cmd)],
+                     ["#!/bin/sh", 'exec {} "$@"'.format(path)],
                      executable=True)
 
   def locate_runfile(self, runfile_path):