fix: ``get_all_relations`` should set ``ALL_RELATIONS`` even on cache hit

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/compose-core

@@ -2491,6 +2491,7 @@ get_all_relations () {
 
     if [ -e "${cache_file}" ]; then
         #debug "$FUNCNAME: SESSION cache hit $1"
+        export ALL_RELATIONS="$cache_file"
         cat "${cache_file}"
         return 0
     fi