[gimp/wip/Jehan/CI-dist-step] gitlab-ci: add a distribution step.

[Jehan <jehanp src gnome org>]

commit 49b71f727ca503acc65cea77b282b255ba81e578
Author: Jehan <jehan girinstud io>
Date:   Fri Aug 7 16:41:05 2020 +0200

    gitlab-ci: add a distribution step.
    
    I don't add this at the end of the distcheck job to make the interface
    clearer, and also because the distcheck job will have full build
    artifacts (allowing to debug a failing distcheck if necessary), whereas
    the `sources` job will just publish tarballs and SHA256 sums generated
    from these tarballs. Simple, clean.

 .gitlab-ci.yml | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3d3ca3ef49..18bf7db3b6 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,6 +5,7 @@ stages:
   - dependencies
   - gimp
   - analysis
+  - distribution
 
 variables:
   GIT_DEPTH: "1"
@@ -158,7 +159,6 @@ gimp-distcheck-debian:
         --enable-gtk-doc
     - make -j "$(nproc)"
     - make -j "$(nproc)" distcheck
-  allow_failure: true
 
 gimp-meson-debian:
   extends: .gimp-debian-base
@@ -329,3 +329,18 @@ cppcheck:
     paths:
       - report
   needs: []
+
+## Ready-to-distribute ##
+
+sources:
+  stage: distribution
+  dependencies:
+    - gimp-distcheck-debian
+  artifacts:
+    when: always
+    paths:
+    - gimp-*.tar.*
+    - SHA256SUMS
+  script:
+    - sha256sum gimp-*.tar.* > SHA256SUMS
+  needs: ["gimp-distcheck-debian"]