[devscripts/prepare_manpage] Fix description strings starting with dash (Closes #10273)

devscripts/prepare_manpage.py

@@ -54,7 +54,11 @@ def filter_options(readme):
 
         if in_options:
             if line.lstrip().startswith('-'):
-                option, description = re.split(r'\s{2,}', line.lstrip())
+                split = re.split(r'\s{2,}', line.lstrip())
+                # Description string may start with `-` as well. If there is
+                # only one piece then it's a description bit not an option.
+                if len(split) > 1:
+                    option, description = split
                     split_option = option.split(' ')
 
                     if not split_option[-1].startswith('-'):  # metavar
@@ -63,7 +67,7 @@ def filter_options(readme):
                     # Pandoc's definition_lists. See http://pandoc.org/README.html
                     # for more information.
                     ret += '\n%s\n:   %s\n' % (option, description)
-            else:
+                    continue
             ret += line.lstrip() + '\n'
         else:
             ret += line + '\n'