Got cheney-play building.

But am back in prior situation where runtime is still failing
the following runtime assertion:

  fatal runtime error:  assertion failed: self.live_allocations > 0

    frame #0: 0x00007fff84ff5212 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff8743eb24 libsystem_c.dylib`pthread_kill + 90
    frame #2: 0x00007fff87482f61 libsystem_c.dylib`abort + 143
    frame #3: 0x000000010001492f cheney-play`rt::util::abort::hb4674cbd08997360e14421923060ba2051ba231925b8cb2e7e28c12656507a49a3::v0.9.pre + 3071
    frame #4: 0x00000001000ea90e cheney-play`rt::local_heap::LocalHeap::free::hae8f8b9f886e684d2e6abe2c4ce537aacce17664887af2eb5bc7515699bb804226ap::v0.9.pre + 670
    frame #5: 0x00000001000779bc cheney-play`rt::local_heap::local_free::h8a617ec6bb1a8e2021faf899d5d9a66bf3e8ba610004108d708529a330179aa9aa::v0.9.pre + 76
    frame #6: 0x000000010000825c cheney-play`_$SP$u32::glue_free::h3bc3db1dbfa883dec5b4ba5704314e5a7d5549d0ea012b04e03db43b4f7e833fa2 + 60
    frame #7: 0x0000000100008211 cheney-play`_$SP$u32::glue_drop::h3bc3db1dbfa883dec5b4ba5704314e5a7d5549d0ea012b04e03db43b4f7e833fa1 + 113
    frame #8: 0x0000000100007ea1 cheney-play`main::h9a8945ce89cad64ddd702578fa37e19946342316d108fc91d6409ab8a7db6d1dav::v0.0 + 497
    frame #9: 0x00000001000e2e18 cheney-play`rt::task::__extensions__::build_start_wrapper::anon::anon::expr_fn::aJ + 104
    frame #10: 0x00000001000e1863 cheney-play`rt::task::__extensions__::run::anon::expr_fn::aB + 67
    frame #11: 0x00000001000fe833 cheney-play`rust_try + 19 at /Users/fklock/Dev/Mozilla/rust-pnkgc/src/rt/rust_cxx_glue.cpp:20
    frame #12: 0x00000001000e1773 cheney-play`rt::task::Unwinder::try::h25e7a74d88e20e9ed54441d6aee16e71fb42d44b19e545c88af4ec9ad90185eeKuaA::v0.9.pre + 67
    frame #13: 0x00000001000e130f cheney-play`rt::task::Task::run::hb010c8566b5e75e53c9fb539451c36a9486e5d6bae30e5c90925787905058e055say::v0.9.pre + 127
    frame #14: 0x00000001000e26ce cheney-play`rt::task::__extensions__::build_start_wrapper::anon::expr_fn::av + 606