This ameliorates use-cases like:
:!cat foo.txt
:make
where the user is interested in the last few lines of output.
Try these shell-based ex-commands before/after this commit:
:grep -r '' *
:make
:!yes
:!grep -r '' *
:!git grep ''
:!cat foo
:!echo foo
:!while true; do date; done
:!for i in `seq 1 20000`; do echo XXXXXXXXXX $i; done
In all cases the last few lines of the command should always be shown,
regardless of where throttling was triggered.