NSSelectorFromString nor sel_getUid do return string itself

gistfile1.m

-(void)testSelectorIdentity {
    NSString* stringA = @"someSelector";
    NSString* stringB = stringA.mutableCopy;
    STAssertTrue(stringA != stringB, @"strings with different identity");

    SEL selA = NSSelectorFromString(stringA);
    SEL selB = NSSelectorFromString(stringB);
    STAssertTrue(selA == selB, @"selectors with same identity (NSSelectorFromString)");

    selA = sel_getUid(stringA.UTF8String);
    selB = sel_getUid(stringB.UTF8String);
    STAssertTrue(selA == selB, @"selectors with same identity (set_getUid)");
}