fix: relation data was forgotten/mixed due to a big cache bug

bin/compose-core

@@ -1827,7 +1827,8 @@ export -f _run_service_action_relation
 
 
 get_relation_data_dir() {
-    local service="$1" target_service="$2" relation_name="$3" cache_file="$state_tmpdir/$FUNCNAME.cache.$1"
+    local service="$1" target_service="$2" relation_name="$3" \
+          cache_file="$state_tmpdir/$FUNCNAME.cache.$(printf "%s\0" "$@" | md5_compat)"
     if [ -e "$cache_file" ]; then
         # debug "$FUNCNAME: cache hit ($*)"
         cat "$cache_file"