Don't allow to go to VI insert mode when the selected buffer is read-only.
Don't allow to go to VI insert mode when the selected buffer is read-only.

ddalex/python-prompt-toolkit,niklasf/python-prompt-toolkit,jonathanslenders/python-prompt-toolkit,ALSchwalm/python-prompt-toolkit,melund/python-prompt-toolkit,amjith/python-prompt-toolkit