FYI, I realize this is manual and doesn't scale, but:

	rpm -e librsvg2-2.2.3-2
	yum install librsvg2
	/usr/bin/update-gdk-pixbuf-loaders i686-redhat-linux-gnu

The last line is the sole failure in the post-install-scriptlet (which refers
to i386-redhat-linux-gnu).

This allowed me to proceed without errors.  I checked the spec file, it has:

%post
/sbin/ldconfig
%{_bindir}/update-gdk-pixbuf-loaders %{_arch}-%{_host_vendor}-%{_host_os}

So %{_arch} turns into i386, while the build target during rpmbuild is
i686-redhat-linux-gnu.  I don't know how they'll _want_ to fix this, but
there you have it.  Personally I'd change %{_arch}, but I don't know to what
it should be changed.

Dan W.