building an older version of a port?

[Lothar Haeger]

See https://trac.macports.org/wiki/howto/InstallingOlderPort and maybe https://www.mail-archive.com/macports-users@lists.macports.org/msg05835.html

> Am 12.08.2020 um 13:54 schrieb Richard L. Hamilton <rlhamil at smart.net>:
> 
> I've forgotten how to do this, can someone explain it? I've fetched the old version of the Portfile corresponding to the version that I want. Specifically, there are some problems thought to be due to bison 3.7 and later, so I want to build bison 3.6.4 (keeping 3.7.1, but deactivated).
>