Intermittent crash in /css21_dev/html4/width-060.htm

[Manishearth]

http://build.servo.org/builders/linux-rel-css/builds/84/steps/test/logs/stdio

Tests with unexpected results:
  ▶ CRASH [expected PASS] /css21_dev/html4/width-060.htm
  │ 
  │ VMware, Inc.
  │ Gallium 0.4 on softpipe
  │ 3.3 (Core Profile) Mesa 12.0.1
  │ called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 32, message: "Broken pipe" } } (thread LayoutThread PipelineId { namespace_id: PipelineNamespaceId(0), index: PipelineIndex(0) }, at ../src/libcore/result.rs:799)
  │ stack backtrace:
  │    0:     0x7fed5c864a3d - backtrace::backtrace::trace::h0e60ef08c7c34e9f
  │    1:     0x7fed5c8650d2 - backtrace::capture::Backtrace::new::h8bf319c36d8f5d1b
  │    2:     0x7fed5c361a9d - servo::main::_{{closure}}::hf8fbab42eb66bcc2
  │    3:     0x7fed5de25ca5 - std::panicking::rust_panic_with_hook::hb1322e5f2588b4db
  │    4:     0x7fed5de25b72 - std::panicking::begin_panic::hfbeda5aad583dc32
  │    5:     0x7fed5de25ab0 - std::panicking::begin_panic_fmt::h4fe9fb9d5109c4bf
  │    6:     0x7fed5de25a31 - rust_begin_unwind
  │    7:     0x7fed5de624bc - core::panicking::panic_fmt::h4395919ece15c671
  │    8:     0x7fed5d23067b - core::result::unwrap_failed::hfcd13129071c9c47
  │    9:     0x7fed5d2327d7 - webrender_traits::api::RenderApi::set_root_stacking_context::h96dbb67ee96f8907
  │   10:     0x7fed5c71d785 - layout_thread::LayoutThread::perform_post_main_layout_passes::hdccb3ad7a4968064
  │   11:     0x7fed5c71c325 - layout_thread::LayoutThread::perform_post_style_recalc_layout_passes::h93809d4c7b781d81
  │   12:     0x7fed5c718b51 - layout_thread::LayoutThread::handle_reflow::h3fa717be2a8a9aab
  │   13:     0x7fed5c70f524 - layout_thread::LayoutThread::handle_request_helper::h3473b257c36d58bf
  │   14:     0x7fed5c70c35f - layout_thread::LayoutThread::handle_request::h3ede86085537e9e0
  │   15:     0x7fed5c69fc3a - std::panicking::try::do_call::h58eea789837f4161
  │   16:     0x7fed5de2e626 - __rust_maybe_catch_panic
  │   17:     0x7fed5c6c8324 - _<F as alloc..boxed..FnBox<A>>::call_box::h5ec23ed23f5d266a
  │   18:     0x7fed5de242e0 - std::sys::thread::Thread::new::thread_start::h022e3887023c6290
  │   19:     0x7fed5a248183 - start_thread
  │   20:     0x7fed59d5f37c - clone
  │   21:                0x0 - <unknown>
  │ ERROR:servo: called `Result::unwrap()` on an `Err` value: Error { repr: Os { code: 32, message: "Broken pipe" } }
  └ Pipeline failed in hard-fail mode.  Crashing!

[Manishearth]

looks like it's in WR cc @glennw