[gnome-shell/wip/fmuellner/more-ci] deal with unset MR_BRANCH_NAME

[Florian Müllner <fmuellner src gnome org>]

commit 38a63e02278d85747936ffab7edc3fce7e62f814
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Feb 12 18:23:39 2019 +0100

    deal with unset MR_BRANCH_NAME
    
    duh.

 .gitlab-ci.yml | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6010c93f0..6aa6cf9b3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -26,10 +26,8 @@ build:
         #- dnf install -y evolution-data-server-devel gjs-devel
         - git clone https://gitlab.gnome.org/GNOME/mutter.git
         - cd mutter
-        - echo $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
-        - MUTTER_BRANCH=$(git branch -l $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME)
-        - echo $MUTTER_BRANCH
-        - echo ${MUTTER_BRANCH:-master}
+        - MUTTER_BRANCH=${CI_MERGE_REQUEST_SOURCE_BRANCH_NAME:-master}
+        - MUTTER_BRANCH=$(git branch -l $MUTTER_BRANCH)
         - git checkout origin/${MUTTER_BRANCH:-master}
         - meson . build
         - ninja -C build