Change logfile open to write mode only

archivebox/config.py

@@ -1157,7 +1157,7 @@ def setup_django(out_dir: Path=None, check_db=False, config: ConfigDict=CONFIG,
         from django.conf import settings
 
         # log startup message to the error log
-        with open(settings.ERROR_LOG, "a+", encoding='utf-8') as f:
+        with open(settings.ERROR_LOG, "a", encoding='utf-8') as f:
             command = ' '.join(sys.argv)
             ts = datetime.now(timezone.utc).strftime('%Y-%m-%d__%H:%M:%S')
             f.write(f"\n> {command}; ts={ts} version={config['VERSION']} docker={config['IN_DOCKER']} is_tty={config['IS_TTY']}\n")