Fix Pylint upgrade issues

* Remove unsupported pylint disable options
    * star-args removed in Pylint 1.4.3
    * abstract-class-little-used removed in Pylint 1.4.3

* Fixes new lint errors

* Copy dummy-variable-rgx expression to new ignored-argument-names expression to ignore unused funtion arguments

* Notable changes
    * Refactor to satisfy Pylint no-else-return warning
    * Fix Pylint inconsistent-return-statements warning
    * Refactor to satisfy consider-iterating-dictionary
    * Remove methods with only super call to satisfy useless-super-delegation
    * Refactor too-many-nested-statements where possible
    * Suppress type checked errors where member is dynamically added (notably derived from josepy.JSONObjectWithFields)
    * Remove None default of func parameter for ExitHandler and ErrorHandler

Resolves #5973

certbot/plugins/util.py

@@ -17,7 +17,7 @@ def get_prefixes(path):
     """
     prefix = path
     prefixes = []
-    while len(prefix) > 0:
+    while prefix:
         prefixes.append(prefix)
         prefix, _ = os.path.split(prefix)
         # break once we hit '/'
@@ -49,8 +49,7 @@ def path_surgery(cmd):
 
     if util.exe_exists(cmd):
         return True
-    else:
-        expanded = " expanded" if any(added) else ""
-        logger.warning("Failed to find executable %s in%s PATH: %s", cmd,
-                       expanded, path)
-        return False
+    expanded = " expanded" if any(added) else ""
+    logger.warning("Failed to find executable %s in%s PATH: %s", cmd,
+                   expanded, path)
+    return False