fixup! 🚧 Use tsv-utils for --output-metadata

Author: victorlin

augur/filter/io.py

@@ -123,7 +123,9 @@ def write_metadata(input_metadata_path: str, delimiters: Sequence[str],
     tsv_join = which("tsv-join")
     cat = get_cat(input_metadata_path)
 
-    # TODO: support compressed outputs when xopen supports them
+    # TODO: support compressed outputs when xopen supports them.
+    # Current error when replacing open() with xopen() and using .xz for output:
+    #     'PipedXzWriter' object has no attribute 'fileno'
     # FIXME: create an issue in the xopen repo
     if output_is_tsv and tsv_join and cat:
         with NamedTemporaryFile(delete=False) as include_file: