I take it this is a result of the aforementioned ABI breakage?
Linking CXX executable imagespec_test
cd /builddir/build/BUILD/oiio-Release-1.5.14/build/linux/src/libOpenImageIO && /usr/bin/cmake -E cmake_link_script CMakeFiles/imagespec_test.dir/link.txt --verbose=1
/usr/bin/c++   -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic  -O2 -g -DNDEBUG   -Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld CMakeFiles/imagespec_test.dir/imagespec_test.cpp.o  -o imagespec_test -rdynamic libOpenImageIO.so.1.5.14 -lboost_filesystem -lboost_regex -lboost_system -lboost_thread -lrt -ldl -lOpenColorIO -lopencv_core -lopencv_highgui -lfreetype -lpng -lz -ltiff -ljpeg -lz -ltiff -ljpeg -lField3D -lhdf5 -lopenjpeg -lwebp -lIlmImf -lgif -lHalf -lIex -lImath -lIlmThread -lpthread -lpugixml -Wl,-rpath,/builddir/build/BUILD/oiio-Release-1.5.14/build/linux/src/libOpenImageIO 
libOpenImageIO.so.1.5.14: undefined reference to `Imf_2_2::Header::name[abi:cxx11]() const'
libOpenImageIO.so.1.5.14: undefined reference to `Imf_2_2::Header::type[abi:cxx11]() const'
collect2: error: ld returned 1 exit status

Thanks,

Richard