Failure during stage1 libcore when removing a drop block from core::unstable

[bstrie]

The Unlock struct in core::unstable contains a drop block. Removing it causes this error:

compile_and_link: x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore.so
/media/linhaus/rust/src/libcore/core.rc:54:7: 54:23 warning: unknown `deny` attribute: `deprecated_self`
/media/linhaus/rust/src/libcore/core.rc:54 #[deny(deprecated_self)];
                                                  ^~~~~~~~~~~~~~~~
/media/linhaus/rust/src/libcore/flate.rs:20:4: 20:18 warning: unused import
/media/linhaus/rust/src/libcore/flate.rs:20 use rand::RngUtil;
                                                ^~~~~~~~~~~~~~
/media/linhaus/rust/src/libcore/stackwalk.rs:83:20: 83:33 warning: argument 1 uses by-copy mode
/media/linhaus/rust/src/libcore/stackwalk.rs:83 fn frame_address(f: &fn(++x: *u8)) {
                                                                    ^~~~~~~~~~~~~
/media/linhaus/rust/src/libcore/rt/uv.rs:225:8: 235:9 warning: argument 3 uses by-copy mode
/media/linhaus/rust/src/libcore/rt/uv.rs:225         extern fn read_cb(stream: *uvll::uv_stream_t,
/media/linhaus/rust/src/libcore/rt/uv.rs:226                           nread: ssize_t, ++buf: Buf) {
/media/linhaus/rust/src/libcore/rt/uv.rs:227             rtdebug!("buf addr: %x", buf.base as uint);
/media/linhaus/rust/src/libcore/rt/uv.rs:228             rtdebug!("buf len: %d", buf.len as int);
/media/linhaus/rust/src/libcore/rt/uv.rs:229             let mut stream_watcher: StreamWatcher =
/media/linhaus/rust/src/libcore/rt/uv.rs:230                 NativeHandle::from_native_handle(stream);
                                             ...
pthread_mutex_destroy(&_mutex) failed in /media/linhaus/rust/src/rt/sync/lock_and_signal.cpp at line 67, result = 16 (Device or resource busy)
Aborted
make: *** [x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore.so] Error 134

[graydon]

assigning bug; change assignment if you disagree

[alexcrichton]

Looks like this was fixed in 2e907a3