Copy metadata properly for temporal filtered sources.

Bug: aomedia:3309
Change-Id: I21b269945d3f6bf4341cacda86accd88148082dc
(cherry picked from commit 5f166b81d805d7b68dbf7310330260dcb56a7e2e)
diff --git a/av1/encoder/encode_strategy.c b/av1/encoder/encode_strategy.c
index b1fff37..76d136c 100644
--- a/av1/encoder/encode_strategy.c
+++ b/av1/encoder/encode_strategy.c
@@ -807,12 +807,16 @@
       if (show_existing_alt_ref) {
         aom_extend_frame_borders(tf_buf_second_arf, av1_num_planes(cm));
         frame_input->source = tf_buf_second_arf;
-        aom_copy_metadata_to_frame_buffer(frame_input->source,
-                                          source_buffer->metadata);
       }
       // Currently INTNL_ARF_UPDATE only do show_existing.
       cpi->common.showable_frame |= 1;
     }
+
+    // Copy source metadata to the temporal filtered frame
+    if (frame_input->source != source_buffer) {
+      aom_copy_metadata_to_frame_buffer(frame_input->source,
+                                        source_buffer->metadata);
+    }
   }
 #if CONFIG_COLLECT_COMPONENT_TIMING
   if (cpi->oxcf.pass == 2) end_timing(cpi, apply_filtering_time);