The .in.in file was added to the repo in 8bdfa6a4e56f. Then Gary added the .in file to POTFILES.in in 1d98555... but I think it should actually be the .in.in file, right?
# SOME DESCRIPTIVE TITLE.
# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
# This file is distributed under the same license as the PACKAGE package.
#
# Translators:
# Shwun Mi <shwunmi@gmail.com>, 2012
# Yin May Oo <yinmayoo@gmail.com>, 2012
msgid""
msgstr""
"Project-Id-Version: Pidgin\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2016-06-15 23:24-0500\n"
"PO-Revision-Date: 2014-11-20 10:22+0000\n"
"Last-Translator: Richard Laager <rlaager@wiktel.com>\n"
#. "Next >" appears on a button on the License Page of the Installer
msgid"Next >"
msgstr"ရှေ့သို့ >"
#. $(^Name) is the current Version name (e.g. Pidgin 2.7.0). $_CLICK will become a translated version of "Click Next to continue." DO NOT translate the CLICK in $_CLICK. It will break the installer.
msgid""
"$(^Name) is released under the GNU General Public License (GPL). The license "
"is provided here for information purposes only. $_CLICK"
msgstr""
"$(^Name) ကို GNU General Public License (GPL) အောက်၌ ထုတ်ပြန်ထားသည်။ ဒီလိုင်စင်ကို ဤနေရာ၌ "