Attaching to existing tmux sessions always creates a new session (named e.g. _session-18419)

I am having this bug, but do you think this is also the cause of the sessions being wiped after disconnecting / reconnecting ? (using f6)

i am having situations like this:

mark@kramidnarg:~⟫ tmux list-sessions
1: 1 windows (created Tue Apr 24 14:12:50 2018) [195x32] (attached)

***create 3 tabs***

mark@kramidnarg:~⟫ tmux list-sessions
1: 3 windows (created Tue Apr 24 14:12:50 2018) [195x32] (attached)

***f6***
***reconnect***

mark@kramidnarg:~⟫ tmux list-sessions
1: 1 windows (created Tue Apr 24 14:13:21 2018) [195x32] (attached)

***f6***
***reconnect***

***type command, open 3 tabs***

mark@kramidnarg:~⟫ tmux list-sessions
1: 3 windows (created Tue Apr 24 14:13:37 2018) [195x32] (attached)
mark@kramidnarg:~⟫

***f6***
***reconnect***

mark@kramidnarg:~⟫ tmux list-sessions
1: 3 windows (created Tue Apr 24 14:13:37 2018) [195x32] (group 1)
_1-27493: 3 windows (created Tue Apr 24 14:14:02 2018) [195x32] (group 1) (attached)

***f6***
***reconnect***

mark@kramidnarg:~⟫ tmux list-sessions
1: 1 windows (created Tue Apr 24 14:14:17 2018) [195x32] (attached)

I am experiencing an issue which I think may be related ever since I updated to Bionic (byobu version: 5.125-0ubuntu1, tmux version: 2.6-3) -- it seems to be correlated with the introduction of the grouped window view (or possibly having it turned on by default).

On my desktop machine I normally have only one byobu session active. Whenever I log back into my X session and need to resume my byobu session (which I do by running byobu with no parameters, which previously worked), I am not asked to choose a session, but I do see this duplicate session behaviour. The duplicate is clearly a duplicate view of the same session, because any change I make in one group is reflected in the other group.

I haven't been able to do anything to eliminate the duplicate view other than killing the session entirely and starting over (which is not what I want).

I have also reproduced the issue in Byobu 5.126, installed from the PPA.

Some more information I have been able to determine through experimentation:

* I can get rid of the duplicate session by using byobu kill-session on the session called 1 (i.e. the first session in the view). I think that I need to be inside a window in the second session, otherwise a new empty session is created.

* Using byobu kill-session on the second session detaches me from the session. The duplicates are still there when I run byobu again, recreated in a new group with a new pid. I experienced identical behaviour when I killed the tmux process with the pid shown in the session name.

* I can only reproduce this by logging out of my X session and logging back in. Just closing the graphical terminal in which byobu is running does not seem to produce the same effect. When I start byobu in a new terminal after that, I get a new *empty* session in addition to the existing session, not a duplicate view.

Today I reproduced the same issue by closing the GUI terminal window in which Byobu was running, and reattaching the session from a new terminal window. I can confirm that `byobu kill-session -t 1` executed from the other session successfully gets rid of one of the duplicate sessions.

I was wondering if there is any progress on this. I prefer using tmux and due to this issue I can't.

This was addressed in byobu 5.124

My use case is to have multiple users connect to an SSH server independently and work in separate tabs. Having a separate session for each client is a desirable feature, not a bug. To spawn a new session for each client,

```
touch ~/.byobu/.reuse-session
```

relevant changelog- https://github.com/dustinkirkland/byobu/blob/c4136ebfe970c31a785fb87468fa08ab7fd7039e/debian/changelog#L11

commit- https://github.com/dustinkirkland/byobu/commit/755c0e9f28b3f8ee57d9c7fc166f0bcbe96577db