For people who have the same problem:
I have tried to install a port that fetches its source from github and it failed to fetch it.
When I tried the fetch command manually for the given URL I saw the following error:
fetch https://github.com/nicolargo/glances/archive/v1.7.3.tar.gz Certificate verification failed for /C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV CA-1 34380826280:error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed:/usr/src/secure/lib/libssl/../../../crypto/openssl/ssl/s3_clnt.c:1168: fetch: https://github.com/nicolargo/glances/archive/v1.7.3.tar.gz: Authentication error
I assume its related to githubs latest improvement to their HTTPS/SSL infrastructure.
To solve this I installed the very latest version of OpenSSL on my FreeBSD 10 machine and afterwards the installation just went fine.