I usually made system properties available for tests runtime using the following closure

test {
    systemProperties['file.encoding'] = 'ISO-8859-1'
    ...
}

On gradle 1.0-rc-1 the following test case fails

import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class MyTest {
	@Test
	public void test1() {
		assertEquals ("ISO-8859-1", System.getProperty ("file.encoding"));
	}
}

It seems a regression, as it worked properly at least on milestone 5, 7 and 8a.
I tried even the latest nightly gradle-1.0-rc-2-20120420064434+0200 just to check if GRADLE-2226 fixed itm, but it still fails.

I've attached the test project.