From 14aa61d2468ba6b630033f652e5e24e39991018b Mon Sep 17 00:00:00 2001
From: Eli Schwartz <eschwartz@archlinux.org>
Date: Mon, 7 Sep 2020 21:35:42 -0400
Subject: [PATCH] Do not print error messages during plugin initialization to
 stdout.

This non-fatal warning emits output during calibredb commands and breaks
scripting.
---
 src/calibre/customize/ui.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/customize/ui.py b/src/calibre/customize/ui.py
index cd1183af9b..7fe802dc0a 100644
--- a/src/calibre/customize/ui.py
+++ b/src/calibre/customize/ui.py
@@ -750,7 +750,7 @@ def initialize_plugins(perf=False):
                 times[plugin.name] = time.time() - st
             _initialized_plugins.append(plugin)
         except:
-            print('Failed to initialize plugin:', repr(zfp))
+            print('Failed to initialize plugin:', repr(zfp), file=sys.stderr)
             if DEBUG:
                 traceback.print_exc()
     # Prevent a custom plugin from overriding stdout/stderr as this breaks