fix: save RunTool command output with correct line endings

Currently RunTool reads command's output with asyncio read, which
returns bytes. This is decoded into python's string and the output already
contains OS specific line endings, which on Windows is CRLF. Problem is
that the command output is saved by using python's text stream/file,
which replaces LF, native python's line ending, with OS specific line ending.
On Windows, and in this particular case, the CRLF from the command output is
translated into CRCRLF and saved in the commands output file. When this
file is read in again, e.g. for hint modules, the CRCRLF is replaced
with LFLF. Again the file is open as text file. Meaning a new emply line
is added.

Fix this by opening the output file with "newline=''", which prevents
this translation. We already have the OS specific line ending in the
command's output.

Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>

tools/idf_py_actions/tools.py

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 import asyncio
 import importlib
@@ -8,7 +8,6 @@ import re
 import subprocess
 import sys
 from asyncio.subprocess import Process
-from io import open
 from pkgutil import iter_modules
 from types import FunctionType
 from typing import Any, Dict, Generator, List, Match, Optional, TextIO, Tuple, Union
@@ -396,7 +395,11 @@ class RunTool:
         last_line = ''
 
         try:
-            with open(output_filename, 'w', encoding='utf8') as output_file:
+            # The command output from asyncio stream already contains OS specific line ending,
+            # because it's read in as bytes and decoded to string. On Windows "output" already
+            # contains CRLF. Use "newline=''" to prevent python to convert CRLF into CRCRLF.
+            # Please see "newline" description at https://docs.python.org/3/library/functions.html#open
+            with open(output_filename, 'w', encoding='utf8', newline='') as output_file:
                 while True:
                     if self.interactive:
                         output = await read_interactive_stream()