Fix "an" usage

[arqunis]

Since the pr i reviewed on got merged way before the author had a chance to quickly change it, i just did it myself. (Or well, someone else asked me to, if you want me to be honest)

[rust-highfive]

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

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[frewsxcv]

Thanks!

@bors r+ rollup

[bors]

📌 Commit a257d5a has been approved by frewsxcv

[Mark-Simulacrum]

@bors retry

[bors]

⌛ Testing commit a257d5a with merge 809b536...

[frewsxcv]

@bors r-

Looks like this hit a test failure: https://travis-ci.org/rust-lang/rust/jobs/229448947 (view the raw log an scroll near the bottom)

We have 'ui tests' that test the error/warning output for rust code. For example, for:

https://github.com/rust-lang/rust/blob/master/src/test/ui/did_you_mean/issue-41679.rs

we have:

https://github.com/rust-lang/rust/blob/master/src/test/ui/did_you_mean/issue-41679.stderr

You'll need to update that '.stderr' file with your 'an' changes

[TimNN]

@bors retry

Since this will fail anyway, prioritize another PR.

[arqunis]

Forgot that you have the change these things as well, but thanks for reminding me.

[Mark-Simulacrum]

@bors r=frewsxcv

[bors]

📌 Commit bb34a3e has been approved by frewsxcv

[bors]

⌛ Testing commit bb34a3e with merge c1a960a...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: frewsxcv
Pushing c1a960a to master...