The heroku-api = 0.4.2 port declares dependency on heroku-api = 0.4.2, which is not satisfied.
A commit references this bug: Author: sunpoet Date: Mon Aug 7 18:52:15 UTC 2017 New revision: 447514 URL: https://svnweb.freebsd.org/changeset/ports/447514 Log: Fix gemspec for heroku-api 0.4.3 - Bump PORTREVISION for package change PR: 221309 Reported by: lifanov Changes: head/www/rubygem-heroku/Makefile head/www/rubygem-heroku/files/patch-gemspec
Committed. Thanks!