install fails - dependency lazy_static cannot compile

✗ cargo -V
cargo 0.20.0 (a60d185c8 2017-07-13)
✗ rustup -V
rustup 1.16.0 (beab5ac2b 2018-12-06)
✗ cargo install -f kailua

    Updating registry `https://github.com/rust-lang/crates.io-index`
  Installing kailua v1.1.0
   Compiling stable_deref_trait v1.1.1
   Compiling unicode-width v0.1.5
   Compiling matches v0.1.8
   Compiling utf8-ranges v1.0.2
   Compiling lazy_static v1.2.0
   Compiling parse-generics-shim v0.1.1
   Compiling serde v1.0.84
   Compiling futures v0.1.25
error: associated constants are experimental (see issue #29646)
  --> /Users/joconnor/.cargo/registry/src/github.com-1ecc6299db9ec823/lazy_static-1.2.0/src/inline_lazy.rs:20:5
   |
20 |     pub const INIT: Self = Lazy(Cell::new(None), ONCE_INIT);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error(s)

error: Could not compile `lazy_static`.
Build failed, waiting for other jobs to finish...
error: failed to compile `kailua v1.1.0`, intermediate artifacts can be found at `/var/folders/08/hxr9shrx3ps72wmxbgtxs4cj84016c/T/cargo-install.2o2RzeGWHcKo`

Caused by:
  build failed

devcat-studio / kailua

install fails - dependency lazy_static cannot compile #23