Also solves the particular problem of installing packages that have multiple versions in the repo, but specifying the exact version would be troublesome:
$ pkg install -n dovecot
The following 2 packages will be installed:
Installing dovecot: 1.2.17
Reinstalling dovecot-2.2.6 (options changed)
$ pkg install -n dovecot-2.2.6
The following 1 packages will be installed:
Reinstalling dovecot-2.2.6 (options changed)
$ pkg install -n -g dovecot-2*
The following 1 packages will be installed:
Reinstalling dovecot-2.2.6 (options changed)