Startup system is not run in "startup_system" Example

[MinerSebas]

Bevy version

a7565e9

Operating system & version

Windows 10 64bit

What you did

I was testing the startup_system example, with cargo run --example startup_system

What you expected to happen

The Terminal should print:

startup system ran first
normal system ran second

What actually happened

The Terminal only printed:

normal system ran second

Additional information

The problem is that startup systems are only run, when app.initialize(); is called, and the only places where this is done is in the ScheduleRunnerPlugin and the WinitPlugin.

Code:

fn main() {
    App::build()
        .add_plugin(bevy::app::ScheduleRunnerPlugin::run_once())

        .add_startup_system(startup_system.system())
        .add_system(normal_system.system())
        .run();
}

Output:

startup system ran first
normal system ran second

Code:

fn main() {
    App::build()
        // Neccesary plugins to avoid Panics
        .add_plugin(bevy_input::InputPlugin::default())
        .add_plugin(bevy_window::WindowPlugin::default())

        // Plugin that allows startup_system to be run
        .add_plugin(bevy_winit::WinitPlugin::default())

        .add_startup_system(startup_system.system())
        .add_system(normal_system.system())
        .run();
}

Output:

startup system ran first
normal system ran second
normal system ran second
normal system ran second
normal system ran second
normal system ran second
[...]

[MinerSebas]

I bisected the commits and found that #690 broke this example