Context dropped before Core causes segfault

If I trigger a move of an instantiated registry object, and then bind listeners to it, they are never invoked. If I trigger a move of a core object then try e.g. .sync(0) - it will Segfault.

struct Example {
  core: Core
}

impl Example {
    fn factory() -> Result<Example> {
        let mainloop = MainLoop::new()?;
        let context = Context::new(&mainloop)?;
        let core = context.connect(None)?;
        let e = Example {
            core,
        };
        Ok(e)
    }
    pub fn crash() -> Result<()> {
        let e= Example::factory()?;
        e.core.sync(0)?; // CRASH
        Ok(())
    }
}