Formatting problem send_mail in version 2.10.0

[Larry Finger]

I have recently switched to openSUSE Leap 42.2 and found that some of the 
features of send_mail no longer work. The problem occurs when trying to add 
information to a Cc to Stable.

The initial pass through the patch produces the output
(body) Adding cc: Stable <sta...@vger.kernel.org> [4.8+] from line 'Cc: Stable 
<sta...@vger.kernel.org> [4.8+]'

That is correct, but the actual Cc list contains
        Stable <sta...@vger.kernel.org[4.8+]>,

The mangled address is not legal and the mail attempt fails.

Thanks,

Larry