[bug] reformatting a Python source code that is in dos fileformat gets damaged after save

I have a Python source code that has dos fileformat. I have a plugin that automatically reformats the code using the black formatter. However, after saving the file, the source code gets damaged. I think the problem is caused by the dos fileformat.

The problematic file is here: https://www.dropbox.com/scl/fi/rsk4u0gj2k33y4vabexn8/dos.py?rlkey=kb4ppmuiufxi865kzmkyvuyre&dl=0

Here is the reformatter plugin:

VERSION = "0.1.4"

local config = import("micro/config")

function init()
    config.MakeCommand("fmt", onSave, config.NoComplete)
end

function onSave(bp)
    local cmd = ""

    local ft = bp.Buf:FileType()
    if ft == "python" then
        cmd = string.format("black --line-length 100 '%s'", bp.Buf.Path)
        reformat(bp, cmd)
    end
end

function reformat(bp, cmd)
    bp:Save()
    local handle = io.popen(cmd)
    local result = handle:read("*a")
    handle:close()
    bp.Buf:ReOpen()
end

If you open this particular file in micro and save it, some lines get damaged. Example:

This line:

    z: str = 'z' if word[0].upper() in MAGANHANGZOK else ''

becomes this:

    z: str = 'z' if wo"d"0].upper() in MAGANHANGZOK else ''

If I run black in the command-line on the file (outside of micro), the file is not damaged.

OS: Linux
micro Version: 2.0.13, Commit hash: 68d88b57

The payload names no repository files or tests. Reproduce with micro 2.0.13, the linked dos.py file, and the provided save/reformat plugin, then trace the save and ReOpen behavior for DOS-format files. Done means saving through this workflow no longer damages source text, while the command-line Black result remains unchanged.