Rebuilt anaconda yields "Couldn't recognize the image file format" GTK error

[Nicolas Martin <nico martin gmail com>]

Hello,

I'm trying to rebuild anaconda and make a custom install CD. I use
anaconda 13.21.117.
Once my rebuilt anaconda loads, the very first screen displays a
python error "An unhandled exception has occurred."

10:14:12,912 ERROR   : unable to read anaconda_header.png: Couldn't
recognize the image file format for file
'/usr/share/anaconda/pixmaps/anaconda_header.png'
10:14:12,912 WARNING : can't find pixmap anaconda_header.png
10:14:13,014 WARNING : /usr/lib/anaconda/gui.py:1585: GtkWarning:
Error loading theme icon 'gtk-go-back-ltr' for stock: Unrecognized
image file format
  self.window.show()

Forgive me for not joining the full python backtrace as I have trouble
attaching files with gmail.

It all comes down to a GTK error in function
gtk.gdk.pixbuf_new_from_file in anaconda/gui.py that returns an error
"Couldn't recognize the image file format for file XXX".
On the screen, instead of icons and graphics, I see a small blank page
with a red cross in it.

The png files are not corrupted, and I can see them using eog for example.

After some investigation, I realized that if I use CENTOS 6 gtk2 RPM
or RHEL6U1 gtk2 RPM for my anaconda rebuild the error does not occur.
However if I use a gtk2 RPM that I compiled myself, with the same spec
as RHEL6U1 or CENTOS 6, then I get the error.
I also noticed that if I install the system using text mode, then I
can use gtk.gdk.pixbuf_new_from_file on the installed system to load a
png without error.

So I assume some special environment must be set up to compile gtk2 in
order to build anaconda. I did try to set XDG_DATA_DIRS to
"/usr/local/share:/usr/share" and then recompile GTK, but without
results.

Thanks in advance for your help.

Regards,

NM