Try env pass-through

buildscript.txt

@@ -4,5 +4,6 @@ clsi
 --acceptance-creds=None
 --dependencies=mongo,redis
 --docker-repos=gcr.io/overleaf-ops
+--env-pass-through=TEXLIVE_IMAGE
 --build-target=docker
 --script-version=1.1.22

docker-compose.ci.yml

@@ -26,6 +26,7 @@ services:
       POSTGRES_HOST: postgres
       MOCHA_GREP: ${MOCHA_GREP}
       NODE_ENV: test
+      TEXLIVE_IMAGE:
     depends_on:
       - mongo
       - redis