IMO better borrow_mut() documentation on RefCell

[gareins]

Previous borrow() is enough to make borrow_mut() panic, no need to have borrow_mut() twice. This

[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. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed.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 CONTRIBUTING.md for more information.

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit de35823 has been approved by steveklabnik

[steveklabnik]

Thanks so much!

[bors]

⌛ Testing commit de35823 with merge f4ab2b3...

[bors]

💔 Test failed - auto-linux-32-nopt-t

[alexcrichton]

@bors: retry

On Sun, Apr 26, 2015 at 10:55 PM, bors [email protected] wrote:

[image: 💔] Test failed - auto-linux-32-nopt-t
http://buildbot.rust-lang.org/builders/auto-linux-32-nopt-t/builds/4696

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Reply to this email directly or view it on GitHub
#24849 (comment).

[bors]

⚡ Previous build results for auto-linux-64-nopt-t, auto-mac-32-opt are reusable. Rebuilding only auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-32-nopt-t, auto-win-32-opt, auto-win-64-nopt-t, auto-win-64-opt...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-32-nopt-t, auto-win-32-opt, auto-win-64-nopt-t, auto-win-64-opt