When I run

sigul --help-commands

it fails with

ERROR:root:Unexpected exception
Traceback (most recent call last):
File "/usr/share/sigul/client.py", line 1755, in main
(config, handler, args) = handle_global_options()
File "/usr/share/sigul/client.py", line 1724, in handle_global_options
print('{0:<20!s}{1!s}'.format(name, help_string))
ValueError: Invalid format specifier

Applying this patch makes it work on Fedora release 33 / Python3.9:

--- client.py.org 2021-03-03 22:27:29.494105008 +0100
+++ client.py 2021-03-03 22:28:46.277726885 +0100
@@ -1721,7 +1721,7 @@
if options.help_commands:
# FIXME: order of the commands
for (name, (_, help_string)) in six.iteritems(command_handlers):
- print('{0:<20!s}{1!s}'.format(name, help_string))
+ print('{0:<20}{1!s}'.format(name, help_string))
sys.exit()
if len(args) < 1:
parser.error('missing command, see --help-commands')