Failure in the test suite when removing drop block from core::task::mod #5380

compile_and_link: x86_64-unknown-linux-gnu/test/stdtest.stage2-x86_64-unknown-linux-gnu
/media/linhaus/rust/src/libstd/std.rc:31:7: 31:23 warning: unknown `deny` attribute: `deprecated_self`
/media/linhaus/rust/src/libstd/std.rc:31 #[deny(deprecated_self)];
                                                ^~~~~~~~~~~~~~~~
/media/linhaus/rust/src/libstd/net_tcp.rs:1470:24: 1470:75 warning: unused import
/media/linhaus/rust/src/libstd/net_tcp.rs:1470                     use net::tcp::test::tcp_ipv4_server_and_client_test::*;
                                                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/media/linhaus/rust/src/libstd/sort.rs:758:8: 758:25 warning: unused import
/media/linhaus/rust/src/libstd/sort.rs:758     use core::prelude::*;
                                                   ^~~~~~~~~~~~~~~~~
/media/linhaus/rust/src/libstd/sort.rs:713:8: 713:25 warning: unused import
/media/linhaus/rust/src/libstd/sort.rs:713     use core::prelude::*;
                                                   ^~~~~~~~~~~~~~~~~
/media/linhaus/rust/src/libstd/flatpipes.rs:941:8: 956:9 warning: argument 1 uses by-copy mode
/media/linhaus/rust/src/libstd/flatpipes.rs:941         fn test_try_recv_none4<P:BytePort>(+loader: PortLoader<P>) {
/media/linhaus/rust/src/libstd/flatpipes.rs:942             fail_unless!(do task::try || {
/media/linhaus/rust/src/libstd/flatpipes.rs:943                 const CONTINUE: [u8 * 4] = [0xAA, 0xBB, 0xCC, 0xDD];
/media/linhaus/rust/src/libstd/flatpipes.rs:944                 // The control word is followed by a valid length,
/media/linhaus/rust/src/libstd/flatpipes.rs:945                 // then undeserializable garbage
/media/linhaus/rust/src/libstd/flatpipes.rs:946                 let len_bytes = do io::u64_to_be_bytes(
                                                ...
run: x86_64-unknown-linux-gnu/test/stdtest.stage2-x86_64-unknown-linux-gnu

running 355 tests
stdtest.stage2-x86_64-unknown-linux-gnu: /media/linhaus/rust/src/rt/rust_task.cpp:647: void rust_task::allow_kill(): Assertion `disallow_kill > 0 && "Illegal allow_kill(): already killable!"' failed.
rust: task failed at 'assertion failed: *one == 2', /media/linhaus/rust/src/libstd/arc.rs:565
Aborted
make: *** [tmp/check-stage2-T-x86_64-unknown-linux-gnu-H-x86_64-unknown-linux-gnu-std.ok] Error 134