fix: newlines for messages in log tail

Author: azzhipa

torchx/cli/cmd_log.py

@@ -64,7 +64,7 @@ def print_log_lines(
             streams=streams,
         ):
             prefix = f"{GREEN}{role_name}/{replica_id}{ENDC} "
-            print(_prefix_line(prefix, line), file=file, end="", flush=True)
+            print(_prefix_line(prefix, line.strip()), file=file, end="\n", flush=True)
     except Exception as e:
         exceptions.put(e)
         raise

torchx/cli/test/cmd_log_test.py

@@ -225,3 +225,11 @@ def test_prefix_line(self) -> None:
         self.assertEqual(
             _prefix_line("<prefix>", "foo\ntest\n"), "<prefix>foo\n<prefix>test\n"
         )
+
+    def test_prefix_line_with_timestamp(self) -> None:
+        # Test that stripping and prefixing works correctly with timestamp logs
+        log_with_timestamp = "2024-01-01T10:00:00.123Z [INFO] - Test message\n"
+        result = _prefix_line("role/0 ", log_with_timestamp.strip())
+        self.assertEqual(
+            result, "role/0 2024-01-01T10:00:00.123Z [INFO] - Test message"
+        )