I believe you can use the following command to test your changes locally:

# this runs all of the tests (not necessary if you know which test is affected)
cargo run --release --features ssl,jit -- -m test -j 1 -u all --slowest --fail-env-changed -v
# this runs only the test suite named "test_whatever" (usually located at `Lib/test/test_whatever.py`)
cargo run --release --features ssl,jit -- -m test -j 1 -u all --slowest --fail-env-changed -v test_whatever

For a list of all resources and more command-line options, you can execute cargo run --release --features ssl,jit -- -m test -h.

If I am failing tests with

# TODO: RUSTPYTHON
    @unittest.expectedFailure

should I remove them?

So the main idea here is that we want to skip iterations when we intersect/difference/symmetric_difference a set with itself. Though the PR fixes faulty assumptions in intersect_update and difference_update (the assumption that the set(s) we supply as an argument isn't the same set as self) it doesn't do the short-circuiting, i.e s = {*range(20)}; s.intersection_update(s, s, s) would iterate over every element in the arguments when it could just skip them all since s &= s is s.

The best approach is along the lines of #3912, we accept objects as arguments for intersection_update/difference_update (AnySet works fine for iand/isub) and compare these objects with is, this is fast O(1) and allows us to ignore sets or clear them depending on the function.