Extends syntax does not seem to work "FATAL: missing 'script' for job"

Summary

extends does not seem to work on the cli, but linter passes it.

Steps to reproduce

How one can reproduce the issue - this is very important

Actual behavior

FATAL: missing 'script' for job 

Expected behavior

Should be same as YAML anchors, which work.

Relevant logs and/or screenshots

FATAL: missing 'script' for job 

Environment description

macOS Mojave

Used GitLab Runner version

Version:      11.3.1~beta.4.g0aa5179e
Git revision: 0aa5179e
Git branch:   11-3-stable
GO version:   go1.8.7
Built:        2018-09-24T16:02:29+0000
OS/Arch:      darwin/amd64