Comment 1 for bug 1618516

OK, after submitting this, I found out that its a duplicate of 525552

So modifying these two files to use the --login option fixes my problem.

bin/byobu-shell
 [ -n "$SHELL" -a -x "$SHELL" ] && exec "$SHELL" --login || exec /bin/sh --login

share/byobu/profiles/tmux
 set -g default-command $SHELL --login

The first one fixes the initial window and the second one fixes any subsequent windows/splits

However, tmux specifically states in the changed file that it wishes, _not_ to read .profile again:
```
# Must set default-command to $SHELL, in order to not source ~/.profile
# BUG: Should *not* hardcode /bin/bash here
set -g default-command $SHELL
```
And indeed, when running tmux on its own (without the --login modification) and adding new windows/splits the aliases from /etc/profile.d/ end .profile are inherited from the original session.

So, somewhere there seems to be a discrepancy how byobu initializes tmux windows.

This is also not a stable solution since as soon as byobu is updated these files will be overwritten.