Wildcard support for artifacts

Summary

Wildcard support for artifacts seems to be broken. A simple wildcard like this:

- a.{rpm,deb}

reports no found files, despite both a.rpm and a.deb existing. Furthermore, starting a path expression with a * fails to validate the yaml, despite being a valid wildcard.

Steps to reproduce

Create the following .gitlab-ci.yml and run the pipeline:

stages:
  - build

build:
  image: docker
  stage: build
  script:
    - touch a.rpm
    - touch a.deb
  artifacts:
    name: "${CI_BUILD_NAME}_${CI_BUILD_REF_NAME}"
    expire_in: '4 hours'
    paths:
      - a.{rpm,deb}

What is the current bug behavior?

WARNING: a.{rpm,deb}: no matching files

What is the expected correct behavior?

The artifacts should be found.

Relevant logs and/or screenshots

Running with gitlab-ci-multi-runner 9.1.0 (0118d89)
  on docker-auto-scale (e11ae361)
Using Docker executor with image docker ...
Using docker image sha256:772ee8f052af831158455a8aaecef4369c28409f1ce7c4e3b21e47cc540e5769 for predefined container...
Pulling docker image docker ...
Using docker image docker ID=sha256:774c3d99c5d5742167cf72c03cb933643b6f27803e50d185c6ff6abb94036a4f for build container...
Running on runner-e11ae361-project-3245424-concurrent-0 via runner-e11ae361-machine-1493983491-2f00effe-digital-ocean-2gb...
Cloning repository...
Cloning into '/builds/martijntje/artifact-wildcards'...
Checking out f873d707 as master...
Skipping Git submodules setup
$ touch a.rpm
$ touch a.deb
Uploading artifacts...
WARNING: a.{rpm,deb}: no matching files            
Uploading artifacts to coordinator... ok            id=15674282 responseStatus=201 Created token=EMPkbxB2
Job succeeded

Output of checks

This bug happens on GitLab.com