Test failure of ilmbase-2.2.0 on i686-linux (testBoxAlgo.cpp)

Greetings from Guix! [0]

We're having trouble building ilmbase-2.2.0 for the i686 architecture on
Linux, with gcc-4.9.3.

The build process fails during testing. Specifically, it fails
testBoxAlgo, like this:

ImathTest: testBoxAlgo.cpp:892: void {anonymous}::boxMatrixTransform(): Assertion `b21 == b2' failed.
/gnu/store/isxqjfaglyfsbcv75y8qbqbph8v28ykr-bash-4.3.39/bin/bash: line 5:  4565 Aborted                 ${dir}$tst

On our mailing list, this was suggested as the nature of the problem
[1]:
On Mon, Nov 30, 2015 at 10:14:49PM +0200, Ludovic Courtès wrote:
> Right.  This sounds very much like a rounding issue, whereby the
> epsilon in floating-point number comparisons is to strict for 32-bit
> machines.

Here is the build system's web page for this particular build...
http://hydra.gnu.org/build/729299
... and the full build log...
http://hydra.gnu.org/build/729299/nixlog/1
... and an exhaustive list of build dependencies (be patient, it
may take a few seconds to load)...
http://hydra.gnu.org/build/729299#tabs-build-deps

We have no problem building on x86_64, armv7, or mips64el.

Thanks for reading,
Leo

[0]
http://www.gnu.org/software/guix/

[1]
http://lists.gnu.org/archive/html/bug-guix/2015-11/msg00179.html