Description of problem:
Gnome shell refuses to start when gtk3 [1] is installed.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=591222

Version-Release number of selected component (if applicable):
gnome-shell-2.29.1-4.i686

How reproducible:
always

Steps to Reproduce:
1. install gtk3
2. try to start gnome-shell
  
Actual results:
When loading gdk-pixbuf-loader it complains that it cannot load version 2.0, because version 3.0 is already loaded (if you need the exact error I can reproduce it later).

Expected results:
Should start without issues.

Additional info:
After removing gtk3, it starts.