Bad behavior when using C-o in insert mode

[neta540]

When using C-o in insert mode, followed by some "enter to insert mode" commands, we enter a buggy "insert mode" which requires to press <Esc> twice in order to exit it, instead of exiting it by pressing <Esc> only once.

To Reproduce

1. Enter insert mode.
2. Type any word.
3. While still in insert mode, press C-o followed by either A, a, I, i, O, o.
4. Press <Esc> once
5. Still in insert mode 😞

Expected behavior
After pressing <Esc>, the expected behavior is to enter normal mode.

Environment

• Extension (VsCodeVim) version: 1.12.4
• VSCode version: 1.41.1
• OS: Linux x64

[cvaldev]

I looked a bit into this. It'd appear to me setting VimState.returnToInsertAfterCommand back to false after entering Insert Mode would fix it. I could make some changes and add some tests.