hi @salimmj,
if you are seeing this on a recent version of PyTorch (v1.5 or nightlies), would you mind filing a github issue?
for a quick local fix, you can also modify the checkpoint data.  Here is a code snippet (for a different case) which is doing something similar:
    def adjust_convbn_metadata(mod, prefix, old_state_dict):
        for name, child in mod._modules.items():
            new_prefix = prefix + '.' + name if prefix != '' else name
            if isinstance(child, torch.nn.intrinsic.qat.ConvBn2d):
                old_state_dict._metadata[new_prefix]['version'] = 2
            adjust_convbn_metadata(child, new_prefix, old_state_dict)
    adjust_convbn_metadata(model, '', checkpoint['model'])