It looks like the new version is having some issue (some string not updated or it's falsely saying it's updated when it's not):
Code:
root@srv2:/usr/local/directadmin/custombuild # ./build letsencrypt
Downloading letsencrypt.sh...
/usr/local/directadmin/custombuild/letsencrypt100% of 21 kB 648 kBps 00m00s
[B]Let's encrypt client 1.0.12 has been installed[/B].
root@srv2:/usr/local/directadmin/custombuild # ./build versions
Latest version of DirectAdmin: 1.51.4
Installed version of DirectAdmin: 1.51.4
Latest version of Let's Encrypt client: 1.0.12
Installed version of Let's Encrypt client: 1.0.11
[B]Let's Encrypt client 1.0.11 to 1.0.12 update is available[/B].