Displaying git trees over the web with pathnames in the URLs
have the unfortunate consequence of URLs getting out-of-date
if files are renamed or deleted from the latest tree.
We can utilize `git log' here to search history and find the
commit which led to the rename or deletion. Of course, we'll
show a suitable command to the user as well, another small
step towards covertly teaching users the git CLI :>
`git log' is not especially fast, here, but Qspawn limiters can
do their job and renames and deletions aren't too common in most
codebases.