vim: Import v8.2.3423

* 8.2.3423: Vim9: list += list creates a new list in :def function
* 8.2.3422: Vim9: no failure if return type differs from returned var
* Update runtime files
* 8.2.3421: a bit of code is not covered by tests
* 8.2.3420: _REENTRANT defined more than once
* 8.2.3419: a failing debug expression may make Vim unusable
* 8.2.3418: garbage collection while evaluating may cause trouble

gitlog.txt

@@ -1 +1 @@
-* [8.2.3417](https://github.com/vim/vim/commit/072f1c68884a1e2d468a0f39e27fc28168fb4b03): Vim9: a failing debug expression aborts script sourcing\n* [8.2.3416](https://github.com/vim/vim/commit/36f691f5f1d0676f080cc97d697d742ed5cc8251): second error is reported while exception is being thrown\n* [8.2.3415](https://github.com/vim/vim/commit/fc3b775055c2361e507a1a44008d5a7d37eecf14): Vim9: not all function argument types are properly checked\n* [8.2.3414](https://github.com/vim/vim/commit/80c88eac5a81dd9f1a96fc80cb8aab6c84fe7b86): fullcommand() gives wrong name with buffer-local user command\n* [8.2.3413](https://github.com/vim/vim/commit/a9e3d560877489acf751f99e045ab1d78e13249c): Vim9: too many characters are allowed in import name
+* [8.2.3423](https://github.com/vim/vim/commit/07802044b90b2cbcc64b2dfe235f019d7c37589c): Vim9: list += list creates a new list in :def function\n* [8.2.3422](https://github.com/vim/vim/commit/efc084e3353d6854b6dac8b240f70cb0abb838ad): Vim9: no failure if return type differs from returned var\n* [Update runtime files](https://github.com/vim/vim/commit/6c391a74fe90190796ca0b0c010112948a6e75d7)\n* [8.2.3421](https://github.com/vim/vim/commit/d176ca3dde47c11aae0376c31b7e1ba0939c8c6c): a bit of code is not covered by tests\n* [8.2.3420](https://github.com/vim/vim/commit/6b9efdde7828b3317b64f38bd90fb5a784a654c0): \_REENTRANT defined more than once\n* [8.2.3419](https://github.com/vim/vim/commit/0325d3967ce7d0fd35bc1472fd476b911b895b76): a failing debug expression may make Vim unusable\n* [8.2.3418](https://github.com/vim/vim/commit/070ac3433b0ebefd6dc6cd49707fcfa1421b9e67): garbage collection while evaluating may cause trouble