No warning about changed file when swiching buffer #235

Describe the bug
When opening an existing buffer in vim, where the associated file has been changed since the buffer was visible the last time, a warning is emitted:

W11: Warning: File "foobar.txt" has changed since editing started
See ":help W11" for more info.
[O]K, (L)oad File:

This does not happen when switching buffers with vim-ctrlspace.

To Reproduce
Steps to reproduce the behavior:

1. Open foobar.txt in vim
2. Open a different buffer, e.g. with :enew
3. Change foobar.txt outside of vim, e.g. echo "TEXT" >> foobar.txt
4. Open the ctrl-space panel
5. Select foobar.txt and press enter

Expected behavior
A warning appears that foobar.txt has been changed outside of vim.

Version(s) (please complete the following information):

• OS: gentoo linux
• Version gvim 8.1.1486

Additional context
In regular vim/gvim the warning appears any time you first switch to the changed buffer. If you decide not to load the changes, the warning will not be shown until the file is changed again outside of vim.

It does not matter how you open the buffer. I tried Ctrl-6 and :b.