🐛 BUG: API/unstable_dev race condition when running several `unstable_dev` commands at the same time

[rozenmd]

What version of Wrangler are you using?

wrangler@beta

What operating system are you using?

Mac

Describe the Bug

In CI, running tests with unstable_dev fails sometimes. Investigating why lead to the following discoveries:

This blows up with TypeError: fetch failed:

    workers.push(
            await wrangler.unstable_dev("src/basicModule.ts"),
            await wrangler.unstable_dev("src/basicModule.ts")
        );

This works:

        workers.push(
            await wrangler.unstable_dev("src/basicModule.ts", { port: 9001 }),
            await wrangler.unstable_dev("src/basicModule.ts", { port: 9002 })
        );

This fails with a jest timeout:

        workers = await Promise.all([
            wrangler.unstable_dev("src/basicModule.ts", { port: 9001 }) as Worker,
            wrangler.unstable_dev("src/basicModule.ts", { port: 9002 }) as Worker,
        ]);