Undocumented sh shell doesn't work
I was trying to do a docker build using the docker:dind image but then I got a
/usr/local/bin/docker-entrypoint.sh: exec: line 19: bash: not founderror message. I saw that shells/bash.go has code that keeps the shell name in variables to support both sh and bash so I tried to have it use a runner that was configured to use the sh shell but then I got a
sh: 3: set: Illegal option -o pipefailerror message.
I guess it's not really a bug because the shell parameter doesn't list sh as an option. It doesn't seem like it would be difficult to add a check for shell == "sh" and not run this set command if it is true though.
