Off by one in upper bound of memory address space

[alexispurslane]

This was pointed out by @baskerville in #28460.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @pcwalton (or someone else) soon.

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[alexcrichton]

r? @steveklabnik

[steveklabnik]

In https://github.com/rust-lang/rust/pull/28441/files, @baskerville pointed out many more of these than just this one.

@baskerville, would you like to modify that PR to only have this change? I appreciate @ChristopherDumas tackling this, but also want to make sure that you get credit for work you had done, if that matters to you.

[baskerville]

@steveklabnik should I create a new pull request?

[steveklabnik]

superceded by #28466

Thanks again for all the quick PRs, @ChristopherDumas .