bash_unit won't work with bash 3

[pgrange]

A user reporting:

I recently ran into some compatibility issues when trying to apply bash_unit on a system that only runs Bash 3 (on a SuSE 11 SP 4). I found the tagged revision v1.1.0 (without the Unicode stuff with \u prints, not supported before Bash 4) a good starting point. The behaviour of ‘set -e’ was changed to Bash 4, causing tests to abruptly die on Bash 3 if a subshell exited with non-zero. I added a check for Bash version before using ‘set -e', and with this change bash_unit seems to run without problems also on Bash 3.

We could at least document that bash_unit currently only have support for >= Bash 4.

[pgrange]

Created this docker image to have bash 3-2 beta to test against. I can reproduce the issue with it.

https://hub.docker.com/r/pgrange/docker-bash-3/