Version 2.15.0-268.18.beta

* Cherry-pick 5331d12f3fd79ce61c588379e24c80d775fe3eab to beta
* Cherry-pick 9b7caf3b93856838dd51053effec3ff37d2c69a4 to beta
* Cherry-pick a856655545e80c58262355e4e9c3af3d928cdfbe to beta
* Cherry-pick 39008c82435fc266e8ac17fefacc1b14afb58bbe to beta
* Cherry-pick 0afb365804ebeec902e0b71ec3550f4359d702fc to beta
* Cherry-pick 23607838084a757c50e952a76e0548adccb984c0 to beta
* Cherry-pick e1428ba9113792118b6b393d71b39798eb32379d to beta
* Cherry-pick ecdcde3a838e1c88c2d00df3b8d36a916b628b49 to beta
* Cherry-pick c4a07a88f9c0a233e40f37fb919c183921c05e96 to beta
* Cherry-pick 9b89231e1e8d4789c82faa8097a83bc6a954f529 to beta
diff --git a/tools/VERSION b/tools/VERSION
index 53fe3f8..e37b1dd 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -28,4 +28,4 @@
 MINOR 15
 PATCH 0
 PRERELEASE 268
-PRERELEASE_PATCH 8
\ No newline at end of file
+PRERELEASE_PATCH 18
\ No newline at end of file