Description of problem:
Byobu appears to source $BYOBU_CONFIG_DIR/.tmux.conf *twice*

Version-Release number of selected component (if applicable):
byobu-5.69-2.fc20.noarch


How reproducible:
Always

Steps to Reproduce:
1. Write a simple .byobu/.tmux.conf file:

[asinha@ankur-laptop ~]$ cat .byobu/.tmux.conf
new-window -ad -n "ncmpcpp"
new-window -ad -n "irssi"
[asinha@ankur-laptop ~]$ 

2. select tmux as backend
3. run byobu

Actual results:
It starts two sessions (bug filed). The one session that does have these windows has them twice. 

Expected results:
Session should only have them once

Additional info:
I dug in a little. So, byobu's command line with tmux is:

asinha   32124  1.5  0.0  22568  2076 ?        Ss   00:18   0:00 tmux -2 -f /usr/share/byobu/profiles/tmuxrc new-session -n - /usr/bin/byobu-shell

Now, tmuxrc sources the following files:
source-file $HOME/.byobu/color.tmux
source-file $BYOBU_CONFIG_DIR/profile.tmux
source-file $BYOBU_CONFIG_DIR/keybindings.tmux
source-file $BYOBU_CONFIG_DIR/.tmux.conf

Note that it's already sourcing $BYOBU_CONFIG_DIR/.tmux.conf

It also sources $BYOBU_CONFIG_DIR/profile.tmux which has the one line:
source $BYOBU_PREFIX/share/byobu/profiles/tmux

This file, again sources $BYOBU_CONFIG_DIR/.tmux.conf in it's last line:
[asinha@ankur-laptop ~]$ tail -2 /usr/share/byobu/profiles/tmux
# Allow local overrides
source $BYOBU_CONFIG_DIR/.tmux.conf

I think this causes duplication of windows.