failed to build, can't find crate event

error[E0463]: can't find crate for `event`
 --> src/launcher/main.rs:4:1
  |
4 | extern crate event;
  | ^^^^^^^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `orbutils`.
warning: build failed, waiting for other jobs to finish...
warning: use of deprecated item 'std::env::home_dir': This function's behavior is unexpected and probably not what you want.
Consider using the home_dir function from https://crates.io/crates/dirs instead.
   --> src/file_manager/main.rs:724:37
    |
724 |         None => if let Some(home) = env::home_dir() {
    |                                     ^^^^^^^^^^^^^
    |
    = note: `#[warn(deprecated)]` on by default

error: build failed

step to reproduce

1. git clone https://gitlab.redox-os.org/redox-os/orbutils.git
2. cd orbutils/
3. cargo build

workaround

add

redox_event = { git = "https://gitlab.redox-os.org/redox-os/event.git" }
redox_syscall = "0.1.51"

to [dependencies] in Cargo.toml seems to work, but other errors occur then.