hyperkitty_import: message["Message-Id"] may fail
When catching a database error the Message-Id field may not be set.
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
utility.execute()
File "/usr/lib/python3/dist-packages/django/core/management/__init__.py", line 356, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 283, in run_from_argv
self.execute(*args, **cmd_options)
File "/usr/lib/python3/dist-packages/django/core/management/base.py", line 330, in execute
output = self.handle(*args, **options)
File "/usr/lib/python3/dist-packages/hyperkitty/management/commands/hyperkitty_import.py", line 350, in handle
importer.from_mbox(mbfile, report_name)
File "/usr/lib/python3/dist-packages/hyperkitty/management/commands/hyperkitty_import.py", line 232, in from_mbox
% (unquote(message["Message-Id"])), report_name)
TypeError: not enough arguments for format string