fix: keep ``COMPOSE_DOCKER_IMAGE`` in subcalls.

bin/compose

@@ -167,6 +167,9 @@ mk_docker_run_options() {
 
     docker_run_opts+=("-v" "$HOME/.docker:/root/.docker")
 
+    COMPOSE_DOCKER_IMAGE=${COMPOSE_DOCKER_IMAGE:-docker.0k.io/compose}
+    docker_run_opts+=("-e" "COMPOSE_DOCKER_IMAGE=$COMPOSE_DOCKER_IMAGE")
+
     COMPOSE_LAUNCHER_BIN=$(readlink -f "${BASH_SOURCE[0]}")
 
     filename=$(mktemp -p /tmp/ -t launch_opts-XXXXXXXXXXXXXXXX)
@@ -196,9 +199,16 @@ run() {
 
     while read-0 opt; do
         docker_run_opts+=("$opt")
+        ## catch COMPOSE_DOCKER_IMAGE
+        if [[ "$env" == "true" && "$opt" == "COMPOSE_DOCKER_IMAGE="* ]]; then
+            COMPOSE_DOCKER_IMAGE=${opt##COMPOSE_DOCKER_IMAGE=}
+        elif [ "$opt" == "-e" ]; then
+            env=true
+        else
+            env=
+        fi
     done < <(cat "$COMPOSE_LAUNCHER_OPTS")
 
-    COMPOSE_DOCKER_IMAGE=${COMPOSE_DOCKER_IMAGE:-docker.0k.io/compose}
     if [ -t 0 ]; then
         docker_run_opts+=("-i")
     fi