Using vyos-1.2.0-rolling-201904260337, it seems that nameservers from dhcp are not properly being set. The config set system disable-dhcp-nameservers was not set.
Steps to reproduce, boot livecd:
Assign dhcp to eth0
config set interfaces ethernet eth0 address dhcp commit save
cat /etc/resolv.conf ### Autogenerated by host_name.py ###
DNS servers are not set.. maybe because host_name.py runs too early?
if you now run sudo /usr/libexec/vyos/conf_mode/host_name.py. It will set /etc/resolv.conf with data from dhcp.