keyboard layout indicator is not shown in mate-panel

[Norbert]

Steps to reproduce:
1a. Install Ubuntu 17.10, install `ubuntu-mate-desktop` package, disable `ibus` in system tray
1b. Install Ubuntu 17.10 MATE beta2 (from http://cdimage.ubuntu.com/ubuntu-mate/releases/17.10/beta-2/ubuntu-mate-17.10-beta2-desktop-i386.iso, SHA256SUM Checksum 21a0a00d121c2178bfb1569abbad46836d656e7b5385a0cc8b6ed51155a56bbf)
2. Configure two keyboard layouts in `mate-control-center` Keyboard - for example English and Russian with <Alt+Shift> layout switcher.

Expected results:
* after adding 2 keyboard layouts "ru"/"en" text is shown in `mate-panel`

Actual results:
* after adding 2 keyboard layouts "ru"/"en" text is not shown in `mate-panel`

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: mate-panel 1.18.4-2
ProcVersionSignature: Ubuntu 4.13.0-12.13-generic 4.13.3
Uname: Linux 4.13.0-12-generic i686
ApportVersion: 2.20.7-0ubuntu2
Architecture: i386
CurrentDesktop: MATE
Date: Sat Oct 7 13:42:40 2017
InstallationDate: Installed on 2017-08-26 (41 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha i386 (20170826)
SourcePackage: mate-panel
UpgradeStatus: No upgrade log present (probably fresh install)

[Norbert (nrbrtx)]

Installation of Ubuntu 17.10 MATE beta2 (from http://cdimage.ubuntu.com/ubuntu-mate/releases/17.10/beta-2/ubuntu-mate-17.10-beta2-desktop-i386.iso, SHA256SUM Checksum 21a0a00d121c2178bfb1569abbad46836d656e7b5385a0cc8b6ed51155a56bbf) gives the same result.