mv: skip the same-file error with -n and --update=none

src/uu/mv/src/mv.rs

@@ -575,6 +575,13 @@ fn assert_not_same_file(
             || source.ends_with("/.")
             || source.is_file())
     {
+        // GNU mv skips the same-file check when it would not replace the
+        // target anyway (-n, --update=none), so this is a silent no-op.
+        if (opts.overwrite == OverwriteMode::NoClobber || opts.update == UpdateMode::None)
+            && source.file_name().is_some()
+        {
+            return Ok(());
+        }
         return Err(MvError::SameFile(source.quote().to_string(), target_display()).into());
     } else if (same_file || canonicalized_target.starts_with(canonicalized_source))
         // don't error if we're moving a symlink of a directory into itself

tests/by-util/test_mv.rs

@@ -562,6 +562,31 @@ fn test_mv_same_file() {
         .stderr_only(format!("mv: '{file_a}' and '{file_a}' are the same file\n"));
 }
 
+#[test]
+fn test_mv_same_file_no_clobber() {
+    // GNU mv does not report "are the same file" when it would not
+    // replace the target anyway; it exits 0 and leaves the file alone.
+    let file_a = "test_mv_same_file_a";
+    for args in [["-n"], ["--update=none"]] {
+        let (at, mut ucmd) = at_and_ucmd!();
+        at.write(file_a, "a");
+        ucmd.args(&args)
+            .arg(file_a)
+            .arg(file_a)
+            .succeeds()
+            .no_output();
+        assert_eq!(at.read(file_a), "a");
+    }
+
+    // --update=none-fail still fails, like GNU
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch(file_a);
+    ucmd.arg("--update=none-fail")
+        .arg(file_a)
+        .arg(file_a)
+        .fails_with_code(1);
+}
+
 #[test]
 #[cfg(all(unix, not(target_os = "android")))]
 #[cfg_attr(