Fix union_relations error when no include/exclude provided

* Fix union_relations error when no include/exclude provided (#509)

* Update CHANGELOG.md

Author: joellabes

CHANGELOG.md

@@ -1,3 +1,7 @@
+# dbt-utils v0.8.2
+## Fixes
+- Fix union_relations error from [#473](https://github.com/dbt-labs/dbt-utils/pull/473) when no include/exclude parameters are provided ([#505](https://github.com/dbt-labs/dbt-utils/issues/505), [#509](https://github.com/dbt-labs/dbt-utils/pull/509))
+
 # dbt-utils v0.8.1
 
 ## New features

macros/sql/union.sql

@@ -61,7 +61,7 @@
 
     {%- set ordered_column_names = column_superset.keys() -%}
 
-    {%- if not column_superset.keys() -%}
+    {% if (include | length > 0 or exclude | length > 0) and not column_superset.keys() %}
         {%- set relations_string -%}
             {%- for relation in relations -%}
                 {{ relation.name }}