OpenEXR: forgot one exception to the rule about squashing non-openexr metadata upon output.
OpenEXR: forgot one exception to the rule about squashing non-openexr metadata upon output.

YangYangTL/oiio,YangYangTL/oiio,OpenImageIO/oiio,sambler/oiio,mcanthony/oiio,scott-wilson/oiio,bdeluca/oiio,sambler/oiio,mcanthony/oiio,cwilling/oiio,cwilling/oiio,OpenImageIO/oiio,scott-wilson/oiio,lgritz/oiio,micler/oiio,scott-wilson/oiio,scott-wilson/oiio,bdeluca/oiio,mcanthony/oiio,lgritz/oiio,micler/oiio,lgritz/oiio,lgritz/oiio,micler/oiio,OpenImageIO/oiio,OpenImageIO/oiio,micler/oiio,bdeluca/oiio,sambler/oiio,cwilling/oiio,sambler/oiio,cwilling/oiio,YangYangTL/oiio,mcanthony/oiio,bdeluca/oiio,YangYangTL/oiio