gst-install is finished when it is not finished actually.

[Shih-Yuan Lee]

Ubuntu 12.04
sessioninstaller: 0.20+bzr128-0ubuntu1.1

Reproduce Steps:
1. Remove some GStreamer plugin by executing `sudo apt-get purge --yes gstreamer0.10-plugins-ugly && sudo apt-get autoremove --purge --yes`.
2. Execute the command `python /usr/share/pyshared/sessioninstaller/gstinstaller.py "gstreamer|0.10|totem|Advanced Streaming Format (ASF) demuxer|decoder-video/x-ms-asf"`.

Expect Result:
It finished after all Debian packages are installed.

Actual Result:
It shows the following messages, but there is a dialog still running the installation.

/usr/lib/python2.7/dist-packages/gobject/constants.py:24: Warning: g_boxed_type_register_static: assertion `g_type_from_name (name) == 0' failed
  import gobject._gobject
INFO:Initializing GStreamerInstaller
DEBUG:Add provide: Advanced Streaming Format (ASF) demuxer|gstreamer0.10(decoder-video/x-ms-asf)
INFO:Finished succesfully

This issue will be relative to Bug #1041032.

It will cause on_plugin_installation_done() of totem-3.0.1/src/backend/bacon-video-widget-gst-missing-plugins.c received GST_INSTALL_PLUGINS_SUCCESS, but it not actually.