issue #477: missing stub-su.py from 137f5fa6c5

tests/data/stubs/stub-su.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+
+import json
+import os
+import subprocess
+import sys
+
+os.environ['ORIGINAL_ARGV'] = json.dumps(sys.argv)
+os.environ['THIS_IS_STUB_SU'] = '1'
+
+# This must be a child process and not exec() since Mitogen replaces its stderr
+# descriptor, causing the last user of the slave PTY to close it, resulting in
+# the master side indicating EIO.
+os.execlp('sh', 'sh', '-c', sys.argv[sys.argv.index('-c') + 1])