Replace obsolete CI variable.

.gitlab-ci.yml

@@ -9,7 +9,7 @@ stages:
 - release
 
 variables:
-  TEST_IMAGE: briar/go-reproducer:${CI_BUILD_REF_NAME}
+  TEST_IMAGE: briar/go-reproducer:${CI_COMMIT_REF_NAME}
   RELEASE_IMAGE: briar/go-reproducer:latest
 
 before_script:
@@ -50,8 +50,8 @@ test_snowflake:
 test_tag:
   stage: test
   script:
-    - docker run -v `pwd`/output:/opt/go-reproducer/output ${TEST_IMAGE} /bin/bash -c "./verify-binary.py obfs4proxy ${CI_BUILD_REF_NAME}"
-    - docker run -v `pwd`/output:/opt/go-reproducer/output ${TEST_IMAGE} /bin/bash -c "./verify-binary.py snowflake ${CI_BUILD_REF_NAME}"
+    - docker run -v `pwd`/output:/opt/go-reproducer/output ${TEST_IMAGE} /bin/bash -c "./verify-binary.py obfs4proxy ${CI_COMMIT_REF_NAME}"
+    - docker run -v `pwd`/output:/opt/go-reproducer/output ${TEST_IMAGE} /bin/bash -c "./verify-binary.py snowflake ${CI_COMMIT_REF_NAME}"
   artifacts:
     paths:
     - output/obfs4proxy