release-notes/5.39.0.md - Add recent PR

release-notes/5.39.0.md

@@ -290,6 +290,10 @@ Released July 7, 2021
   ([dev/core#2479](https://lab.civicrm.org/dev/core/-/issues/2479):
   [20059](https://github.com/civicrm/civicrm-core/pull/20059))**
 
+- **Fatal error while upgrading smart-group data
+  ([dev/core#2659](https://lab.civicrm.org/dev/core/-/issues/2659):
+  [20756](https://github.com/civicrm/civicrm-core/pull/20756/))**
+
 - **CRM_Utils_File::isAbsolute does not respect PHP stream wrappers (Work
   Towards [dev/core#2590](https://lab.civicrm.org/dev/core/-/issues/2590):
   [20270](https://github.com/civicrm/civicrm-core/pull/20270))**