[polari] ci: Wait for 'check-commit-log' before continuing

[Florian Müllner <fmuellner src gnome org>]

commit c548756f5644ffb340bcea9fca6bf5b32839578b
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Nov 6 18:07:07 2020 +0100

    ci: Wait for 'check-commit-log' before continuing
    
    The check-commit-log is quick, and to get a result early is helpful as
    one can then more quickly check for failures via the report provided via
    the JUnit report.
    
    https://gitlab.gnome.org/GNOME/polari/-/merge_requests/170

 .gitlab-ci.yml                 | 3 +--
 .gitlab-ci/check-commit-log.sh | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d34fe1b2..e38cbe16 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -20,8 +20,7 @@ check_commit_log:
     stage: review
     script:
         - ./.gitlab-ci/check-commit-log.sh
-    only:
-        - merge_requests
+    <<: *only_default
     artifacts:
         expire_in: 1 week
         paths:
diff --git a/.gitlab-ci/check-commit-log.sh b/.gitlab-ci/check-commit-log.sh
index 4462cfcb..68645ce3 100755
--- a/.gitlab-ci/check-commit-log.sh
+++ b/.gitlab-ci/check-commit-log.sh
@@ -1,8 +1,8 @@
 #!/usr/bin/env bash
 
 if [ -z "$CI_MERGE_REQUEST_TARGET_BRANCH_NAME" ]; then
-  echo Cannot review non-merge request
-  exit 1
+  echo This is not a merge request, skipping
+  exit 0
 fi
 
 git fetch $CI_MERGE_REQUEST_PROJECT_URL.git $CI_MERGE_REQUEST_TARGET_BRANCH_NAME