terminal size changes are not detected

[Junyeong Jang]

Hi, all.
please follow these steps..

$ screen
$ stty size
48 80
(resize the terminal window ...)
$ stty size
73 182
(hmm.. it works well...
now change session name to something,
then resize the window again)
$ stty size
73 182
(oops... the window size is not changed!)

The debug log shows why this happens.
Screen tried to open the old (default) path of a socket file,
but the file is renamed when the session name is changed.
this maybe a bug?

(..... debug log ......)
AttacherWinch()
Attach: how=6, tty=/dev/pts/2
secopen(/tmp/uscreens/S-flips/14114.pts-2.happy, 0x801, 0000)
MakeClientSocket() open /tmp/uscreens/S-flips/14114.pts-2.happy failed (2)