"git review --setup" failed in Chinese locale

If a subcommand's output includes a non-ASCII character, the following
occurs:

[nova]$ LANG=zh_CN.UTF-8 LC_ALL=zh_CN.UTF-8 git review --setup
Traceback (most recent call last):
  File "/usr/bin/git-review", line 1187, in <module>
    print(e)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 180-183: ordinal not in range(128)

Python3 works, because we force-encode everyting in run_command_status.

Change-Id: Ic4f4b0df57068c356a670901e02bf00c33985e2c
Merge ""git review --setup" failed in Chinese locale"