[utils] write_string: Workaround newline issue in conhost

On windows `conhost`, when `WINDOWS_VT_MODE` is enabled, `\n` is not
actually sent if the window is exactly the length of printed line,
and the line does not end with a white-space character. So the
line-break disappears when resizing the window.

Fixes #1863

yt_dlp/YoutubeDL.py

@@ -3580,7 +3580,7 @@ def print_debug_header(self):
         def get_encoding(stream):
             ret = str(getattr(stream, 'encoding', 'missing (%s)' % type(stream).__name__))
             if not supports_terminal_sequences(stream):
-                from .compat import WINDOWS_VT_MODE
+                from .compat import WINDOWS_VT_MODE  # Must be imported locally
                 ret += ' (No VT)' if WINDOWS_VT_MODE is False else ' (No ANSI)'
             return ret
 

yt_dlp/utils.py

@@ -1851,6 +1851,10 @@ def write_string(s, out=None, encoding=None):
     assert isinstance(s, str)
     out = out or sys.stderr
 
+    from .compat import WINDOWS_VT_MODE  # Must be imported locally
+    if WINDOWS_VT_MODE:
+        s = s.replace('\n', ' \n')
+
     if 'b' in getattr(out, 'mode', ''):
         byt = s.encode(encoding or preferredencoding(), 'ignore')
         out.write(byt)