Fix deepcopy of Dataset and Sequence

[CPBridge]

Describe the changes

Fix for #1813.

In the __deepcopy__ methods of Sequence and Dataset, the returned object should be initialised to an instance of the type of self rather than the literal Dataset and Sequence types. This way the methods also work for subclasses.

Since this has caused some significant issues with highdicom, wsiDicomizer, and possibly other libraries, would you consider a 2.4.1 patch release for this fix?

Tasks

• [ x] Unit tests added that reproduce the issue or prove feature is working
• [ x] Fix or feature added
• [ x] Code typed and mypy shows no errors
• Documentation updated (if relevant)
  • No warnings during build
  • Preview link (CircleCI -> Artifacts -> doc/_build/html/index.html)
• [ x] Unit tests passing and overall coverage the same or better

[darcymason]

Thanks for this, Chris. As soon as I saw it I had a d'oh! moment - of course the class names should not have been used directly.

would you consider a 2.4.1 patch release for this fix?

Absolutely, I'll see if I can publish it right away, but if any problems come up it may be a day or two.

[darcymason]

I'll see if I can publish it right away, but if any problems come up it may be a day or two.

Well, not enough time -- other commitments, but I will try for later today.

[CPBridge]

Thanks Darcy!

[darcymason]

Ok, 2.4.1 has been published.