I'm aware of those two flags to start each prompt in normal mode:
let g:vimshell_enable_start_insert = 0
let g:vimshell_enable_stay_insert = 0
However, how can I switch back to normal mode while typing the current command? I would like to edit the typed command before executing it, using normal mode navigation. <esc> or <c-c> have no effect for me.