Default view transform missing on config copy

[mdecaria]

Default view transform is dropped on config copy using the equal operator.

Python reproduction

import PyOpenColorIO as ocio
config = ocio.Config.CreateFromFile("ocio://default")
config.getDefaultViewTransformName()
'Un-tone-mapped'
ocio.SetCurrentConfig(config)
ocio.GetCurrentConfig().getDefaultViewTransformName()
''

C++ reproduction

OCIO::ConstConfigRcPtr config = OCIO::Config::CreateFromBuiltinConfig("ocio://default");
std::cerr << "config 1 "<< config->getDefaultViewTransformName() << std::endl;
OCIO::ConstConfigRcPtr config2 = config->createEditableCopy();
std::cerr << "config 2 " << config2->getDefaultViewTransformName() << std::endl;

Output:
config 1 Un-tone-mapped
config 2