Also posted as github issue.
This was on centos 7.2.x.
I ran the LE client v0.4.2 with following CLI options:
./letsencrypt-auto certonly -a webroot --webroot-path -c /etc/letsencrypt/cli.ini -d
my cli.ini contains:
server = https://acme-v01.api.letsencrypt.org/directory
after obtaining a cert just now, it congratulated me with the standard finishing output dialog and i received my cert and all seemed normal except it outputted at the very end the following line:
./letsencrypt-auto: line 1810: tag: command not found