MultiMutation duplicates specs on Retry, causing SUBDOC_INVALID_COMBO.

The _mutateCommands field is populated during WriteBody, to be used later by GetCommandValues().  However, since Reset() is not overridden, it is never cleared.  Subsequent calls to WriteBody add the same specs to _mutateCommands, possibly exceeding the 16 spec limit and causing an error.

 

{Name=\"SUBDOC_INVALID_COMBO\", Description=\"Subdoc: Lookup and mutation commands found within single packet\", Attributes=\"subdoc,invalid-input\"}