misc/53564: tmux: pagination/wordwrap misalingment

[cspencer%gmail.com@localhost]

>Number:         53564
>Category:       misc
>Synopsis:       tmux: pagination/wordwrap misalingment
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Aug 31 18:20:00 +0000 2018
>Originator:     Courtney Spencer
>Release:        NetBSD 8.0_RC2
>Organization:
>Environment:
System: NetBSD masavana.p 8.0_RC2 NetBSD 8.0_RC2 (GENERIC) #0: Mon Jun 25 13:01:26 UTC 2018 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC i386
Architecture: i386
Machine: i386
>Description:
        On a default install, regardles of shell or TERM, tmux
when reading long lines, writes the output to the terminal
by breaking up then entire string insets of two line breaks with an
unread, but added line break. 

>How-To-Repeat:
In 8.x, start a tmux session.

Write a one-line string to the terminal such that the number of 
characters is greater than
2 * $COLUMNS + 1:

For purposes of demonstration, I'm using 480 characters written to an
80 column terminal.

jot -s "" -b L 480

Double click to select the output, or click and drag to select.
When double-clicking, the highlited area will be exactly two lines
regardless of how long the string is and how much it wraps.
When highlighting and draging, write the selction to a temp
file and notice there are multiple lines.  In my example above
480 characters becomes 3 lines.
>Fix: