installing an older version of a port in the github era

[Ken Cunningham]

So as we move further into github, it is becoming of interest to
sometimes find a previous version of a port within the macports git
era. These instructions
<https://trac.macports.org/wiki/howto/InstallingOlderPort> work fine
up until the move to github.

It's easy enough to find the portfile of interest, and to roll back in
the history of that single portfile to previous versions. But it's
also necessary to download any associated files in the files directory
for the port that match that portfile at that time, and that part
appears a bit more difficult.

Looking at <http://stackoverflow.com/questions/600079/how-do-i-clone-a-subdirectory-only-of-a-git-repository/13738951#13738951>
for an efficient use of space I *think* what needs to be done is a
sparse checkout (of only the directory holding the port) with a
shallow clone (to get the port at that point in time but not the whole
history) at a specific point in the commit history (to get the version
you want).

Ugh. There are steps for the sparse checkout of the shallow clone
there in the stackoverflow example, but the part about the specific
point in the commit history is not there yet.

Any ideas? perhaps just do a sparse checkout without a shallow clone,
and go back in the history that way?

Thanks, Ken