[skip ci] Update .po files

Autobuild bot on TravisCI · Autobuild bot on TravisCI · commit 1041bc96fb20 · 2018-05-04T13:10:33.000+09:00
diff --git a/reference/expressions.po b/reference/expressions.po
@@ -10,7 +10,7 @@ msgstr ""
 "Project-Id-Version: Python 2.7\n"
 "Report-Msgid-Bugs-To: \n"
 "POT-Creation-Date: 2018-01-21 01:52+0900\n"
-"PO-Revision-Date: 2018-01-20 03:07+0000\n"
+"PO-Revision-Date: 2018-05-03 15:48+0000\n"
 "Last-Translator: cocoatomo\n"
 "Language-Team: Japanese (http://www.transifex.com/python-doc/python-27/language/ja/)\n"
 "MIME-Version: 1.0\n"
