Consider the following script:
cat > missing-signcolumn.vim << EOF
call setline('.', ['abc', 'def', 'ghi'])
diffthis
vnew
call setline('.', ['abc', 'ghi'])
sign define xxx text=EE
sign place 1 line=1 name=xxx buffer=2
diffthis
EOF
vim -u NONE -S missing-signcolumn.vim
It produces the following result:
http://img-fotki.yandex.ru/get/5608/kp-pav.1/0_69590_4e0c4429_orig.png.
Here you can see that diff filler line is missing signs column line.
missing-signcolumn.vim
Description: application/wine-extension-vim
<<inline: screenshot-2011-06-04@17:12:27:875874070.png>>
signature.asc
Description: This is a digitally signed message part.
