mate-disk-usage-analyzer: closing prefs window resets the "excluded-uris" setting to the default (empty)

[monsta]

Steps to reproduce:

1. Run mate-disk-usage-analyzer.
2. Run dconf-editor and set the "excluded-uris" setting in org.mate.disk-usage-analyzer.preferences to some directory. I placed 'file:///home/monsta/Dropbox' there (note the single quotes and the uri format).
3. Open the preferences window in mate-disk-usage-analyzer. Actually, you can open it before changing anything in dconf-editor - it doesn't matter.
4. Close the preferences window.
5. See the "excluded-uris" setting in dconf-editor resetting to the default (empty).

Reproduced in Debian Jessie with MATE 1.9 (from git master).

Note: this is not related to that GLib 2.43 issue - it's reproducible with GLib 2.42 just fine.

--- Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/9470194-mate-disk-usage-analyzer-closing-prefs-window-resets-the-excluded-uris-setting-to-the-default-empty?utm_campaign=plugin&utm_content=tracker%2F1509859&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F1509859&utm_medium=issues&utm_source=github).