Use a more robust method of validating an encoding.

evennia/commands/default/account.py

@@ -21,6 +21,7 @@ method. Otherwise all text will be returned to all connected sessions.
 from builtins import range
 
 import time
+from codecs import lookup as codecs_lookup
 from django.conf import settings
 from evennia.server.sessionhandler import SESSIONS
 from evennia.utils import utils, create, search, evtable
@@ -533,7 +534,7 @@ class CmdOption(COMMAND_DEFAULT_CLASS):
         def validate_encoding(new_encoding):
             # helper: change encoding
             try:
-                b"test-string".decode(new_encoding)
+                codecs_lookup(new_encoding)
             except LookupError:
                 raise RuntimeError("The encoding '|w%s|n' is invalid. " % new_encoding)
             return val

evennia/commands/default/unloggedin.py

@@ -3,6 +3,7 @@ Commands that are available from the connect screen.
 """
 import re
 import time
+from codecs import lookup as codecs_lookup
 from collections import defaultdict
 from random import getrandbits
 from django.conf import settings
@@ -481,7 +482,7 @@ class CmdUnconnectedEncoding(COMMAND_DEFAULT_CLASS):
             old_encoding = self.session.protocol_flags.get("ENCODING", None)
             encoding = self.args
             try:
-                utils.to_str(b"test-string".decode(encoding))
+                codecs_lookup(encoding)
             except LookupError:
                 string = "|rThe encoding '|w%s|r' is invalid. Keeping the previous encoding '|w%s|r'.|n"\
                          % (encoding, old_encoding)

evennia/server/inputfuncs.py

@@ -21,6 +21,7 @@ settings.INPUT_FUNC_MODULES.
 from future.utils import viewkeys
 
 import importlib
+from codecs import lookup as codecs_lookup
 from django.conf import settings
 from evennia.commands.cmdhandler import cmdhandler
 from evennia.accounts.models import AccountDB
@@ -176,7 +177,7 @@ def client_options(session, *args, **kwargs):
     def validate_encoding(val):
         # helper: change encoding
         try:
-            b"test-string".decode(val)
+            codecs_lookup(val)
         except LookupError:
             raise RuntimeError("The encoding '|w%s|n' is invalid. " % val)
         return val