Description of problem:
Tried to run gnome-tweak-tool 3.9.90 on current Fedora Rawhide.

Version-Release number of selected component:
gnome-tweak-tool-3.9.90-1.fc20

Additional info:
reporter:       libreport-2.1.6
cmdline:        python /usr/bin/gnome-tweak-tool
executable:     /usr/bin/gnome-tweak-tool
kernel:         3.11.0-0.rc6.git1.2.fc20.x86_64
runlevel:       N N
type:           Python
uid:            1001

Truncated backtrace:
tweak_group_startup.py:146:__init__:TypeError: constructor returned NULL

Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/gtweak/app.py", line 39, in do_activate
    self.win = Window(self, model)
  File "/usr/lib/python2.7/site-packages/gtweak/tweakview.py", line 51, in __init__
    self._model.load_tweaks(self)
  File "/usr/lib/python2.7/site-packages/gtweak/tweakmodel.py", line 119, in load_tweaks
    mods = __import__("gtweak.tweaks", globals(), locals(), tweak_files, 0)
  File "/usr/lib/python2.7/site-packages/gtweak/tweaks/tweak_group_startup.py", line 202, in <module>
    AutostartListBoxTweakGroup(),
  File "/usr/lib/python2.7/site-packages/gtweak/tweaks/tweak_group_startup.py", line 146, in __init__
    df = Gio.DesktopAppInfo.new_from_filename(f)
TypeError: constructor returned NULL

Local variables in innermost frame:
files: ['/home/adamw/.config/autostart/xfce4-settings-helper-autostart.desktop', '/home/adamw/.config/autostart/epiphany.desktop', '/home/adamw/.config/autostart/evolution.desktop', '/home/adamw/.config/autostart/gnome-terminal.desktop', '/home/adamw/.config/autostart/firefox.desktop', '/home/adamw/.config/autostart/revelation.desktop', '/home/adamw/.config/autostart/gnome-keyring-gpg.desktop', '/home/adamw/.config/autostart/gnome-keyring-secrets.desktop', '/home/adamw/.config/autostart/gnome-keyring-pkcs11.desktop', '/home/adamw/.config/autostart/gnome-keyring-ssh.desktop', '/home/adamw/.config/autostart/xfconf-migration-4.6.desktop', '/home/adamw/.config/autostart/gedit.desktop']
tweaks: []
self: <AutostartListBoxTweakGroup object at 0x2ec2370 (uninitialized at 0x0)>
f: '/home/adamw/.config/autostart/xfce4-settings-helper-autostart.desktop'