Add regression test for #17756

[frewsxcv]

Closes #17756

[rust-highfive]

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

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[alexcrichton]

@bors: r+ d8680f6

[bors]

⌛ Testing commit d8680f6 with merge e6596d0...

[bors]

💔 Test failed - auto-mac-32-opt

[alexcrichton]

@bors: retry

On Mon, Jun 29, 2015 at 9:37 PM, bors notifications@github.com wrote:

[image: 💔] Test failed - auto-mac-32-opt
http://buildbot.rust-lang.org/builders/auto-mac-32-opt/builds/5574

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#26668 (comment).

[bors]

⚡ Previous build results for auto-linux-64-nopt-t, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-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-32-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-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-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt