test_offscreen_texture_formats_store_rgba16161616 failure comparing rgba16_green after float conversion

 34/185 mutter:cogl+cogl/conform / cogl-test-offscreen-texture-formats-gles2

ERROR:../src/tests/cogl/conform/test-offscreen-texture-formats.c:102:test_offscreen_texture_formats_store_rgba16161616:
 assertion failed (pixel_data[1] == rgba16_green): (61132 == 61133)
not ok /offscreen/texture-formats/store-rgba16161616 -
 ERROR:../src/tests/cogl/conform/test-offscreen-texture-formats.c:102:test_offscreen_texture_formats_store_rgba16161616:
 assertion failed (pixel_data[1] == rgba16_green): (61132 == 61133)

From https://bugs.launchpad.net/bugs/2073009