Forward RUSTFLAGS.

Author: Alexhuszagh

ci/test-docker-in-docker.sh

@@ -16,7 +16,7 @@ home=$(dirname "${source}")
 
 main() {
     docker run -v "${home}":/project \
-        -w /project --rm -e TARGET \
+        -w /project --rm -e TARGET -e RUSTFLAGS \
         -v /var/run/docker.sock:/var/run/docker.sock \
         docker:18.09-dind sh -c '
 #!/usr/bin/env sh