Version 2.9.0-21.4.beta

* Cherry-pick 66cb8a8ed841a3a245f07aa878de311e8c60988f to beta
* Cherry-pick 897706edbdbdd1e08601387b95dc931edde55e75 to beta
diff --git a/tools/VERSION b/tools/VERSION
index 4cf53fd..c041bdd 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -34,6 +34,6 @@
 MINOR 9
 PATCH 0
 PRERELEASE 21
-PRERELEASE_PATCH 2
+PRERELEASE_PATCH 4
 ABI_VERSION 38
 OLDEST_SUPPORTED_ABI_VERSION 38