[Users] FYI: Forward modifies header

[Pierre Fortin]

First noticed this in CM3 git63.  These screenshots taken in git91.

Selected a previously sent message (fwd1.png) in Sent folder, clicked
Forward (fwd2.png).

To: field is wrapped which is OK; but the Subject is no longer on its own
line.

Selected Recipients and pasted them to To: (fwd3.png) and they are in a
single To: field with a NEWLINE character.

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