[AIRFLOW-XXX] Bump version to 1.9.0 again.
diff --git a/airflow/version.py b/airflow/version.py
index cbd7901..2eddb9e 100644
--- a/airflow/version.py
+++ b/airflow/version.py
@@ -13,4 +13,4 @@
 # limitations under the License.
 #
 
-version = '1.9.0+incubating'
+version = '1.9.0'