fixed PY-12024 "Replace mutable default argument" quickfix outputs non-standard formatting

python/src/com/jetbrains/python/inspections/quickfix/PyDefaultArgumentQuickFix.java

@@ -74,7 +74,7 @@ public class PyDefaultArgumentQuickFix implements LocalQuickFix {
       }
       str.append("):\n\tpass");
       PyIfStatement ifStatement = elementGenerator.createFromText(LanguageLevel.forElement(function), PyIfStatement.class,
-                                                "if not " + defName + ": " + defName + " = " + defaultValue.getText());
+                                                "if not " + defName + ":\n\t" + defName + " = " + defaultValue.getText());
 
       PyStatement firstStatement = list.getStatements()[0];
       PyStringLiteralExpression docString = function.getDocStringExpression();

python/testData/inspections/DefaultArgument_after.py

@@ -1,3 +1,4 @@
 def foo(args=None):
-    if not args: args = []
+    if not args:
+        args = []
     pass