[TS-2497] Failed post results in tunnel buffers being returned to freelist prematurely, Reporter: Thomas Jackson <thjackso@linkedin.com>

Conflicts:
	CHANGES
TS-2463: Crash regression around slow-log feature

This happens when logging a slow event, and fixes commit c290ce0df2a.

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	CHANGES
TS-2452: Can't access a deleted object

It's an obvious bug, blame me:(.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>

Conflicts:
	CHANGES (also, fix merge artifacts in this file from previous
	cherry-picking)