"thread has no syscall_condition" warning during fork-shadow test

[stevenengler]

When running the fork-shadow test, there are two warnings about not having a syscall condition during interrupt_with_signal(). I'm not sure if this is important, so I figured I'd make an issue for it.

./setup test fork-shadow
less build/Testing/Temporary/LastTest.log

... [process.rs:501] [shadow_rs::host::process] thread ThreadId(1056) has no syscall_condition. How?
... [process.rs:501] [shadow_rs::host::process] thread ThreadId(1058) has no syscall_condition. How?

shadow/src/main/host/process.rs

Lines 482 to 507 in 73bdff2

	fn interrupt_with_signal(&self, host: &Host, signal: Signal) {
	let threads = self.threads.borrow();
	for thread in threads.values() {
	let thread = thread.borrow(host.root());
	{
	let thread_shmem = thread.shmem();
	let host_lock = host.shim_shmem_lock_borrow().unwrap();
	let thread_shmem_protected = thread_shmem.protected.borrow(&host_lock.root);
	let blocked_signals = thread_shmem_protected.blocked_signals;
	if blocked_signals.has(signal) {
	continue;
	}
	}
	let Some(mut cond) = thread.syscall_condition_mut() else {
	// Defensively handle this gracefully, but it probably shouldn't happen.
	// The only thread in the process not blocked on a syscall should be
	// the current-running thread (if any), but the caller should have
	// delivered the signal synchronously instead of using this function
	// in that case.
	warn!("thread {:?} has no syscall_condition. How?", thread.id());
	continue;
	};
	cond.wakeup_for_signal(host, signal);
	break;
	}
	}