import SCons
class CustomCacheDir1(SCons.CacheDir.CacheDir):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        print("INSTANCIATED %s" % str(type(self).__name__))

    @classmethod
    def copy_to_cache(cls, env, src, dst):
        print("MY_CUSTOM_CACHEDIR_CLASS1")
        super().copy_to_cache(env, src, dst)

class CustomCacheDir2(SCons.CacheDir.CacheDir):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        print("INSTANCIATED %s" % str(type(self).__name__))

    @classmethod
    def copy_to_cache(cls, env, src, dst):
        print("MY_CUSTOM_CACHEDIR_CLASS2")
        super().copy_to_cache(env, src, dst)

env = Environment(tools=[])
env.CacheDir('cache1', CustomCacheDir1)
env.CacheDir('cache2', CustomCacheDir2)

# two cachedirs were initialized, but the second one was the most recent
# and should remain in the cloned environment, even when we switch the
# original environment back. The cachedir2 should be the only copy_to_cache
# function we call.
cloned = env.Clone()
cloned.Command('file.out', 'file.in', Copy('$TARGET', '$SOURCE'))

env.CacheDir('cache1', CustomCacheDir1)