fix short name checks for regulation groups

Author: nmaarnio

arho_feature_template/gui/dialogs/plan_feature_form.py

@@ -114,7 +114,12 @@ def _check_regulation_group_short_names(self) -> bool:
             if not short_name:
                 continue
 
-            if short_name in self.existing_group_short_names:
+            if (
+                not (
+                    reg_group_widget.regulation_group.id_ and short_name == reg_group_widget.regulation_group.short_name
+                )
+                and short_name in self.existing_group_short_names
+            ):
                 existing_names.add(short_name)
             if short_name in seen_names:
                 duplicate_names.add(short_name)

arho_feature_template/gui/dialogs/plan_regulation_group_form.py

@@ -146,7 +146,13 @@ def _initalize_regulation_from_config(self, config: RegulationConfig, parent: QT
 
     def _check_short_name(self) -> bool:
         short_name = self.short_name.text()
-        if short_name and short_name in self.existing_group_short_names:
+
+        if not short_name:
+            return True
+        if (
+            not (self.regulation_group.id_ and short_name == self.regulation_group.short_name)
+            and short_name in self.existing_group_short_names
+        ):
             msg = f"Kaavamääräysryhmä lyhyellä nimellä '<b>{short_name}</b>' on jo olemassa."
             QMessageBox.critical(self, "Virhe", msg)
             return False