Version 2.9.0-21.10.beta

* Cherry-pick c632a629ffa47182dc74a024a12928bb3fc23ac0 to beta
* Cherry-pick 3844e74adbcc55a933180aef9bb4408c3b851cfa to beta
* Cherry-pick 7e5ac71ff390bd140ebe77b19e698bd808d8b927 to beta
* Cherry-pick a38e265f04d8976d226c3d966de2d9070a5c0941 to beta
* Cherry-pick 90bba3ae277dacf561a188d8f1d0d6f0756d597f to beta
* Cherry-pick f6a82443e47a17be471ef104b5de2549fdf797e9 to beta
diff --git a/tools/VERSION b/tools/VERSION
index c041bdd..40e02d0 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -34,6 +34,6 @@
 MINOR 9
 PATCH 0
 PRERELEASE 21
-PRERELEASE_PATCH 4
+PRERELEASE_PATCH 10
 ABI_VERSION 38
 OLDEST_SUPPORTED_ABI_VERSION 38