cygwin+subst issue

testcase.c

#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>

int main() {
	const char const* fn = "foo";
	int handle1, handle2, res;
	
	handle1 = open(fn, O_RDONLY | O_CREAT);
	if (handle1 == -1) {
		perror("open #1");
	}
	
	res = unlink(fn);
	if (res == -1) {
		perror("unlink");
	}
	
	handle2 = open(fn, O_WRONLY | O_CREAT);
	if (handle2 == -1) {
		perror("open #2");
	}
	
	close(handle2);
	close(handle1);
	
	return 0;
}

testcase.sh

#!/usr/bin/bash
touch foo
{ rm foo; touch foo; } <foo