Strange behavior with headers in FastAPI

[spikerwork]

When your running local wrangler dev based on example in documentation here https://developers.cloudflare.com/workers/languages/python/packages/fastapi/

I see strange response headers, contains b'' strings

PS. I am using npx wrangler@3.55.0 dev bc latest wrangler version not working at all.

[hoodmane]

I think this is fixed by cloudflare/workerd#2125