Accidental name bindings with structural pattern matching

Bug report

Your environment

• CPython versions tested on: 3.10.2, 3.11.0a6
• Operating system and architecture: macOS Monterey, Version 12.3.1. Mac mini running M1, Apple silicon.

Steps to reproduce:

Run the code in bug.py, attached.

bug.zip

The output on my Mac mini is:

% python bug.py
Cheese Sandwich

Search for 'match' in the code. Notice that one of the terms matches
the only str in the list, "Cheese Sandwich". Later we create a dataclass
of type PersonHeight. On the last line of the file, we print the type
of one of the fields in a PersonHeight object. Note that it is not <class 'str'> as it should be,
but "Cheese Sandwich"

If we comment out the match expression, we get the correct behavior
(see comment below in code)