mpremote: unable to execute fs commands - mpremote.transport.TransportError: could not enter raw repl

Port, board and/or hardware

esp32 wroom

MicroPython version

MicroPython v1.23.0 on 2024-06-02; Generic ESP32 module with ESP32
mpremote 1.24.0

Reproduction

mpremote fs ls failed with
mpremote.transport.TransportError: could not enter raw repl

Expected behaviour

expected

mpremote fs ls
ls :
           0 mrequests/

Observed behaviour

b'MicroPython v1.23.0 on 2024-06-02; Generic ESP32 module with ESP32\r\nType "help()" for more information.\r\n>>> '
Traceback (most recent call last):
  File "/opt/homebrew/bin/mpremote", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/opt/homebrew/lib/python3.11/site-packages/mpremote/main.py", line 538, in main
    handler_func(state, args)
  File "/opt/homebrew/lib/python3.11/site-packages/mpremote/commands.py", line 294, in do_filesystem
    state.ensure_raw_repl()
  File "/opt/homebrew/lib/python3.11/site-packages/mpremote/main.py", line 480, in ensure_raw_repl
    self.transport.enter_raw_repl(soft_reset=soft_reset)
  File "/opt/homebrew/lib/python3.11/site-packages/mpremote/transport_serial.py", line 139, in enter_raw_repl
    raise TransportError("could not enter raw repl")
mpremote.transport.TransportError: could not enter raw repl

Additional Information

My temporary workaround is additional time.sleep(1) at line
https://github.com/micropython/micropython/blob/0e490b7c8f32bb72c516985abe67147b9385dc34/tools/mpremote/mpremote/transport_serial.py#L125
before flush input.

Code of Conduct

Yes, I agree

Start with tools/mpremote/mpremote/transport_serial.py around line 125 and trace the raw-REPL setup called by ensure_raw_repl from do_filesystem. Reproduce the failure with mpremote fs ls on the reported ESP32 and compare it with the additional one-second delay workaround. Done means filesystem commands enter the raw REPL reliably without that workaround.