I have attached a patch.
Thank you for suggesting.

`env_script_all_files` is very cool method.
I wrote a wrapper for byobu using this method, but another problem arises.

When a new shell starts, `byobu-launch` executes automatically by user settings. 
This commands launches byobu for the first time or exit immediately otherwise.

In wrapper, `byobu-launch` consists of `exec /brabrabra/byobu-launch`.
So, when `byobu-launch` exits because it is not the first time launching, a shell itself ends up being terminated.

(In fact, if `byobu-launch` wrapper doesn't use `exec` and just only executes, it doesn't work fine. This maybe a problem of byobu. [I have reported to upstream.](https://bugs.launchpad.net/byobu/+bug/1289157))

I hard-coded `export BYOBU_PREFIX=$(brew --prefix)` in this patch, so scripts works even if not using wrapper. (but a bit messy)