sort: compare strings before comparing hashes

Since lines that compare equal should be sorted together, we need to first
compare the lines (taking settings into account). Only if they do not compare
equal we should compare the hashes.

tests/by-util/test_sort.rs

@@ -235,6 +235,16 @@ fn test_random_shuffle_two_runs_not_the_same() {
     }
 }
 
+#[test]
+fn test_random_ignore_case() {
+    let input = "ABC\nABc\nAbC\nAbc\naBC\naBc\nabC\nabc\n";
+    new_ucmd!()
+        .args(&["-fR"])
+        .pipe_in(input)
+        .succeeds()
+        .stdout_is(input);
+}
+
 #[test]
 fn test_numeric_floats_and_ints() {
     test_helper(