From 67fa7c9bbbfcf41a009c35125338b7a49bdc4bb7 Mon Sep 17 00:00:00 2001
From: Ruben Vorderman <r.h.p.vorderman@lumc.nl>
Date: Mon, 9 Oct 2023 08:55:33 +0200
Subject: [PATCH] Add a comment why igzip_threaded.open's defer capability is
 not used

---
 src/xopen/__init__.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/xopen/__init__.py b/src/xopen/__init__.py
index 151517c..66464a4 100644
--- a/src/xopen/__init__.py
+++ b/src/xopen/__init__.py
@@ -1048,6 +1048,8 @@ def _open_external_gzip_writer(
 
 def _open_gz(filename, mode: str, compresslevel, threads, **text_mode_kwargs):
     assert mode in ("rt", "rb", "wt", "wb", "at", "ab")
+    # With threads == 0 igzip_threaded defers to igzip.open, but that is not
+    # desirable as a reproducible header is required.
     if igzip_threaded and threads != 0:
         try:
             return igzip_threaded.open(