weex -v report DeprecationWarning: OutgoingMessage.prototype._headers is deprecate

[ixqbar]

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Your development environment

• Check weex-toolkit verison (Run weex -v)
• Detact what's wrong with your environment (Run weex doctor)
• Which platform (Win/Mac/Ubuntu..)

The key error stack message.

weex -v
(node:18775) [DEP0066] DeprecationWarning: OutgoingMessage.prototype._headers is deprecate

Steps to reproduce the problem.(Maybe a dotwe link)