Windows: Generate catalog: Workaround for systems where a broken antivirus or similar holds open files in the catalog library causing a permission denied error. Fixes #2115084 [Create Catalog fails](https://bugs.launchpad.net/calibre/+bug/2115084)

src/calibre/gui2/convert/gui_conversion.py

@@ -5,6 +5,7 @@ __docformat__ = 'restructuredtext en'
 import os
 from optparse import OptionParser
 
+from calibre.constants import iswindows
 from calibre.customize.conversion import DummyReporter, OptionRecommendation
 from calibre.customize.ui import plugin_for_catalog_format
 from calibre.ebooks.conversion.plumber import Plumber
@@ -80,6 +81,10 @@ def gui_catalog(library_path, temp_db_path, fmt, title, dbspec, ids, out_file_na
         plugin = plugin_for_catalog_format(fmt)
         return plugin.run(out_file_name, opts, db, notification=notification)
     finally:
-        import shutil
         db.close()
-        shutil.rmtree(os.path.dirname(temp_db_path))
+        from calibre.db.backend import rmtree_with_retry
+        try:
+            rmtree_with_retry(temp_db_path)
+        except PermissionError:
+            if not iswindows:  # probably some antivirus holding a file open, the folder will be deleted on exit anyway
+                raise