test: follow canonical directory root artifacts

test/sep/importdir_test.ww

@@ -100,11 +100,11 @@ fn samefile(a: str, b: str, why: str) void = {
 	let wantroot: str = strings.concat("//ww:module-reset main\n", appsrc,
 		"\n");
 	if (!testenv.same(wantroot, testenv.readfile(strings.concat(cwork,
-		"__root.unit.ww")))) {
+		"main.unit.ww")))) {
 		fail("root unit is not exactly its owned source");
 	};
 	let keys: []str = ["example.base", "example.bar", "example.foo",
-		"__root"];
+		"main"];
 	let suffixes: []str = [".unit.ww", ".wwi", ".a"];
 	i = 0;
 	for (i < keys.len) {