Request an example for the comment about discarding the common prefix and suffix

[Albert Jin]

Hi,

I am referring to this,

http://www.gnu.org/software/diffutils/manual/html_node/diff-Performance.html

[quote]
Normally diff discards the prefix and suffix that is common to both files 
before it attempts to find a minimal set of differences. This makes diff run 
faster, but occasionally it may produce non-minimal output. The 
--horizon-lines=lines option prevents diff from discarding the last lines lines 
of the prefix and the first lines lines of the suffix. This gives diff further 
opportunities to find a minimal output.
[/quote]

Is there an example to support this conclusion that if the common prefix and 
suffix are discarded first, the result is not minimal?

Thanks,
Albert