[cesarb]

That's because `UnexpectedEof` is never returned from `read()`, it's only ever returned from `read_exact()`. In fact, `UnexpectedEof` didn't exist originally, it was added together with `read_exact()` to represent its unique error case (which is: `read()` returned end-of-file, but we still needed more bytes to completely fill the buffer). It's an error to return `UnexpectedEof` from any of the other methods of the `Read` trait, and since it's an error, it makes sense for `read_to_end()` to stop and propagate that error.

(In fact, thinking better about it, there are some cases where `read()` could legitimately return `UnexpectedEof`, like when it's a wrapper for a compressed stream which has fixed-size fields, and that stream was truncated in the middle of one of these fields. It's clear that, in that case, `UnexpectedEof` is not an end-of-file for the wrapper; it should be treated as an I/O error.)