Make CmdSet.add respect allow_duplicates=True. Resolve #3601

CHANGELOG.md

@@ -36,6 +36,7 @@
   un-pickle-able object and cause an error at server shutdown (Griatch)
 - [Fix][issue3649]: The `:j` command in EvEditor would squash empty lines (Griatch)
 - [Fix][issue3560]: Tutorial QuestHandler failed to load after server restart (Griatch)
+- [Fix][issue3601]: `CmdSet.add(..., allow_duplicates=True)` didn't allow duplicate cmd keys (Griatch)
 - [Doc][pull3801]: Move Evennia doc build system to latest Sphinx/myST
   (PowershellNinja, also honorary mention to electroglyph)
 - [Doc][pull3800]: Describe support for Telnet SSH in HAProxy documentation (holl0wstar)
@@ -67,6 +68,7 @@
 [issue3813]: https://github.com/evennia/evennia/issues/3513
 [issue3649]: https://github.com/evennia/evennia/issues/3649
 [issue3560]: https://github.com/evennia/evennia/issues/3560
+[issue3601]: https://github.com/evennia/evennia/issues/3601
 
 
 ## Evennia 5.0.1

evennia/commands/cmdset.py

@@ -549,17 +549,19 @@ class CmdSet(object, metaclass=_CmdSetMeta):
             if not hasattr(cmd, "obj") or cmd.obj is None:
                 cmd.obj = self.cmdsetobj
 
-            # remove duplicates and add new
-            for _dum in range(commands.count(cmd)):
-                commands.remove(cmd)
+            if not allow_duplicates:
+                # remove duplicates and add new
+                for _dum in range(commands.count(cmd)):
+                    commands.remove(cmd)
             commands.append(cmd)
 
             # add system_command to separate list as well,
             # for quick look-up. These have no
             if cmd.key.startswith("__"):
-                # remove same-matches and add new
-                for _dum in range(system_commands.count(cmd)):
-                    system_commands.remove(cmd)
+                if not allow_duplicates:
+                    # remove same-matches and add new
+                    for _dum in range(system_commands.count(cmd)):
+                        system_commands.remove(cmd)
                 system_commands.append(cmd)
 
         if not allow_duplicates:

evennia/commands/tests.py

@@ -1309,6 +1309,21 @@ class TestCmdSet(BaseEvenniaTest):
 
         self.assertIsInstance(result, _CmdTest2)
 
+    def test_cmdset_add_allow_duplicates(self):
+        class _CmdDuplicateA(Command):
+            key = "duplicate"
+
+        class _CmdDuplicateB(Command):
+            key = "duplicate"
+
+        cmdset = CmdSet()
+        cmdset.add(_CmdDuplicateA, allow_duplicates=True)
+        cmdset.add(_CmdDuplicateB, allow_duplicates=True)
+
+        duplicate_cmds = [cmd for cmd in cmdset.commands if cmd.key == "duplicate"]
+        self.assertEqual(len(duplicate_cmds), 2)
+        self.assertEqual({cmd.__class__ for cmd in duplicate_cmds}, {_CmdDuplicateA, _CmdDuplicateB})
+
 
 class _CmdG(Command):
     key = "smile"