This is a revised (but still ugly) revision of the original snippet that
I think details somewhat what I mean by detecting the relevant changes
to these types of commits and adding something to indicate this. I'd
really like to see this be on the same line, instead of having two
[source] blocks. But, as noted before, not a pro in Yasnippet by any
means. :) (not to mention, the elisp is not good, but it is a rough
concept).