Reorder Gitlab CI jobs

 + Create a stage for other versions of the compiler, making the most
 significant more visible.
 + This allows to reorder and push test for 4.02 between 4.01 and 4.03.

.gitlab-ci.yml

@@ -1,23 +1,16 @@
 stages:
   # Test with alpine
   - test
+  # Test with alpine, other version of the compiler
+  - other_version
   # Real distrubutions
   - real
 
-# OCaml version 4.02
-ocaml_402:
-  before_script:
-    - sudo apk update && sudo apk add m4
-  stage: test
-  image: ocaml/opam:alpine_ocaml-4.02.3
-  script: "./gitlab-ci.sh"
-  allow_failure: false
-
 # OCaml version 4.00
 ocaml_400:
   before_script:
     - sudo apk update && sudo apk add m4
-  stage: test
+  stage: other_version
   image: ocaml/opam:alpine_ocaml-4.00.1
   script: "./gitlab-ci.sh"
   allow_failure: true
@@ -26,25 +19,34 @@ ocaml_400:
 ocaml_401:
   before_script:
     - sudo apk update && sudo apk add m4
-  stage: test
+  stage: other_version
   image: ocaml/opam:alpine_ocaml-4.01.0
   script: "./gitlab-ci.sh"
   allow_failure: true
 
+# OCaml version 4.02
+ocaml_402:
+  before_script:
+    - sudo apk update && sudo apk add m4
+  stage: test
+  image: ocaml/opam:alpine_ocaml-4.02.3
+  script: "./gitlab-ci.sh"
+  allow_failure: false
+
 # OCaml version 4.03
 ocaml_403:
   before_script:
     - sudo apk update && sudo apk add m4
-  stage: test
+  stage: other_version
   image: ocaml/opam:alpine_ocaml-4.03.0
   script: "./gitlab-ci.sh"
   allow_failure: true
 
-# OCaml version 4.03
+# OCaml version 4.03, with flambda optimisation
 ocaml_403_flambda:
   before_script:
     - sudo apk update && sudo apk add m4
-  stage: test
+  stage: other_version
   image: ocaml/opam:alpine_ocaml-4.03.0_flambda
   script: "./gitlab-ci.sh"
   allow_failure: true