Failed to input verification code if pam-google-authenticator is setuped

[Ｖ字龍(Vdragon)]

Issue reproduce steps
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1. Install and properly setup to use pam-google-authenticator package
2. Try to authenticate yourself using PolicyKit1-KDE

Expected behavior
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User successfully authenticated after input account password, then the TOTP generated by Google Authenticator

Abnormal behavior
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The "Verification code:" textbox appeared non-modifyable thus the authentication process can't complete.(as the attached screenshot shown)

Reporter's environment
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* Ubuntu 14.04LTS using kubuntu-ppa/backports PPA
* polkit-kde-1 package version: 0.99.1-1

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: polkit-kde-1 0.99.1-1
Uname: Linux 3.15.0-031500rc5-lowlatency x86_64
ApportVersion: 2.14.1-0ubuntu3.3
Architecture: amd64
CurrentDesktop: KDE
Date: Thu Aug 7 05:50:44 2014
ExecutablePath: /usr/lib/kde4/libexec/polkit-kde-authentication-agent-1
InstallationDate: Installed on 2014-04-13 (115 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326)
SourcePackage: polkit-kde-1
UpgradeStatus: No upgrade log present (probably fresh install)

[Ｖ字龍(Vdragon) (vdragon)]

Upstream bug report:
https://bugs.kde.org/show_bug.cgi?id=338080