Just for clarification for future readers;

I landed a PR that used f"{x=}" in some new functionalities, and that broke the buildbots, the buildbots do test that many of the `Lib/` files can be round-tripped ast->unparse->ast, and as ast-unparse did not understood f-debug, if roundtripped f"{x=}" to f"{x!r}". The PRs CIs did not fail as apparently they don't test this functionality.

So currently not having support for f-string-debug in ast-unparse kind of prevent using f-string debug format in the stdlib.

I'm happy if `expr_text` get removed, and having unparse round-trip to `x={x!r}` sounds sufficient to me; it may make like of formatters like black a bit harder maybe ? Though I believe black is likely not using ast but lib2to3.