Can't open preferences since 1a3cbe3c on an installed meld (local is fine)

[Scott Kostyshak <skostysh princeton edu>]

Hi,

On a recent checkout of meld (25c40916), preferences do not open for
me and I get the following output on the terminal:

$ meld

(meld:2974): Gtk-WARNING **: unable to set child property `menu-label'
of type `gchararray' from value of type `PyObject'
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/meld/meldapp.py", line
101, in preferences_callback
    meld.preferences.PreferencesDialog(self.get_active_window())
  File "/usr/local/lib/python2.7/dist-packages/meld/preferences.py",
line 166, in __init__
    "sizegroup_editor", "timestampstore"])
  File "/usr/local/lib/python2.7/dist-packages/meld/ui/gnomeglade.py",
line 45, in __init__
    self.builder.add_objects_from_file(filename, objects)
gi._glib.GError: Invalid object type `GSettingsStringComboBox'
scott wws-2:~/lyxbuilds/master$

Bisect leads me to the following:

commit 1a3cbe3c7c815914c882ed9a1a5ad034115ba1ce
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Thu Apr 24 06:26:27 2014 +1000

    Add gsetting and initial UI for merge file order preference

I'm on Ubuntu 14.04 and I install meld with the command
sudo ./setup.py install --prefix "/usr"

I can run meld fine locally with ./bin/meld and have no particular
need to use the latest Git version. I'm just testing for fun (and so
that I can make some feature requests knowing they haven't been
implemented).

Note that when testing, I did not uninstall any previous version so I
cannot rule out the possibility of some previously used files causing
problems (which would be my fault). Let me know if you want me to look
into this possibility.

Am I missing a dependency?

Thanks for all of your work, Kai and others!

Best,

Scott