The new oldtest directory is in test/old/testdir. The reason for this is
that many tests have hardcoded the parent directory name to be
'testdir'.

Problem:    Vim9: blob operations not fully tested.
Solution:   Make more blob tests run in Vim9 script.  Fix filter().  Make
            insert() give an error for a null blob, like add().

https://github.com/vim/vim/commit/39211cba723a2cb58a97c7e08826713164b86efc

vim-patch:8.2.3284: no error for insert() or remove() changing a locked blob

Problem:    No error for insert() or remove() changing a locked blob.
Solution:   Check a blob is not locked before changing it. (Sean Dewar,
            closes vim/vim#8696)

https://github.com/vim/vim/commit/80d7395dcfe96158428da6bb3d28a6eee1244e28

Co-authored-by: Bram Moolenaar <Bram@vim.org>
Co-authored-by: Sean Dewar <seandewar@users.noreply.github.com>

Problem:    Vim9: not all blob operations work.
Solution:   Run more tests also with Vim9 script and :def functions.  Fix what
            doesn't work.

https://github.com/vim/vim/commit/0e3ff1919603ee4c4a347fdf761dbdbdeb068015

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    Accessing invalid memory when a regular expression checks the
            Visual area while matching in a string.
Solution:   Do not try matching the Visual area in a string.

https://github.com/vim/vim/commit/679d66c2d21dfe03d0f89b9a818b0aaebb4c3b87

Use CheckScriptFailure() instead of v9.CheckScriptFailure().

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    Lambda for option that is a function may be garbage collected.
Solution:   Set a reference in the funcref. (Yegappan Lakshmanan,
            closes vim/vim#9330)

https://github.com/vim/vim/commit/6ae8fae8696623b527c7fb22567f6a3705b2f0dd

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>