[gnome-games/wip/exalm/ci] ci: Enable sources repositories for Ubuntu job

[Alexander Mikhaylenko <alexm src gnome org>]

commit 6ddbee55581c33e18241e049ba370fa1ad265375
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Sat Oct 20 01:40:50 2018 +0500

    ci: Enable sources repositories for Ubuntu job

 .gitlab-ci.yml | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index f2dc830d..3205f4db 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -94,6 +94,8 @@ ubuntu:devel:
   image: ubuntu:devel
   stage: cross_distro
   before_script:
+    # Enable source repositories, this is required for `apt-get build-dep`
+    - sed -i -e 's/# deb-src/deb-src/' /etc/apt/sources.list
     - apt-get update
     - apt-get install -y git
     - apt-get build-dep -y libmanette retro-gtk gnome-games-app