[sandbox/bash] Use protocol 2 for env dumping.
@@ -38,7 +38,7 @@ class BashSandbox(Sandbox):
tmp_path = os.path.realpath(tmp[1])
cmd = "bash -l -c 'source \"{0}\"; python -c \"" \
- "import os,pickle;pickle.dump(dict(os.environ),open(\\\"{1}\\\",\\\"wb\\\"))\"'"
+ "import os,pickle;pickle.dump(dict(os.environ),open(\\\"{1}\\\",\\\"wb\\\"),protocol=2)\"'"
cmd = cmd.format(script, tmp_path)
returncode, out, _ = interruptable_popen(cmd, shell=True, executable="/bin/bash",
