rshell fails serial usb connection where `picocom --baud 115200 --lower-rts --lower-dtr /dev/ttyUSB0` succeeds

[arkanoid87]

$ rshell --buffer-size 512 --wait 20 --port /dev/ttyUSB0 --baud 115200 --rts 0 --dtr 0 -d

Debug = True
Port = /dev/ttyUSB0
Baud = 115200
User = micro
Password = python
Wait = 20
List = 0
nocolor = 0
ascii = 0
Timing = 0
Quiet = 0
BUFFER_SIZE = 512
Cmd = []
Using buffer-size of 512
Connecting to /dev/ttyUSB0 (buffer-size 512)...
Trying to connect to REPL ....................Unable to connect to REPL

$ picocom --baud 115200 --lower-rts --lower-dtr /dev/ttyUSB0

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:4656
load:0x40078000,len:13284
ho 0 tail 12 room 4
load:0x40080400,len:3712
entry 0x4008064c
MicroPython v1.20.0 on 2023-04-26; ESP32 module (spiram) with ESP32
Type "help()" for more information.
>>>

surprisingly, /dev/ttyUSB0 is available for connection from other programs like picocom while rshell is Trying to connect to REPL. Not sure if this is meaningful or not