This reverts commit 8bda66a737.
The change causes issues with ParamSpec implementations in type
checkers, at least pyright and my work-in-progress support for
ParamSpec in mypy. It's not yet clear how to fix the issues, so I
think that it's best to revert this, at least temporarily until we've
found a good solution. See #6347 for context.
Eliminated the use of "bare" TypeVars (i.e. a TypeVar that appears only once) within generic methods. While not considered an error in PEP 484, these are a common source of bugs in code, and some type checkers (including pytype and pyright) flag them as errors.
Co-authored-by: Eric Traut <erictr@microsoft.com>
