str_replace_editor doesn't preserve the encoding properly for non-ASCII characters.

[pekkah-vincit]

Describe the bug

Run into a issue where "ä" was not encoded properly after edit and shows up as triangle with question mark . Copilot itself reported this to be caused by " str_replace_editor doesn't preserve
the encoding properly for non-ASCII characters."

Affected version

No response

Steps to reproduce the behavior

1. Ask Copilot to modify C# files with comments if Finnish for example "// Täysi"
2. Copilot does changes which include the comment line
3. "ä" character is corrupted

Expected behavior

No character corruption

Additional context

copilot ---version
0.0.341
Commit: 5725358

[williammartin]

Oof, thanks for the report! Definitely something for us to look into.