Fixed a cause of NPEs in MailImpl.setMessage when the new message was the same of the previous message (JAMES-609)
Fixed a cause of NPEs in MailImpl.setMessage when the new message was the same of the previous message (JAMES-609)

git-svn-id: 88158f914d5603334254b4adf21dfd50ec107162@442573 13f79535-47bb-0310-9956-ffa450edef68

chibenwa/james,rouazana/james,aduprat/james,rouazana/james,chibenwa/james,chibenwa/james,rouazana/james,aduprat/james,aduprat/james,chibenwa/james,rouazana/james,aduprat/james