Use bash executable consistently (#7909)
Use bash executable consistently (#7909)

Merge pull request 7909
ryanshaw/jekyll,tillgrallert/jekyll,fulldecent/jekyll,ryanshaw/jekyll,x-way/jekyll,yhironaka/yhironaka.github.io,jaybe-jekyll/jekyll,x-way/jekyll,x-way/jekyll,jaybe-jekyll/jekyll,chrisfinazzo/jekyll,chrisfinazzo/jekyll,jekyll/jekyll,jekyll/jekyll,fulldecent/jekyll,tillgrallert/jekyll,jaybe-jekyll/jekyll,fulldecent/jekyll,jekyll/jekyll,jaybe-jekyll/jekyll,chrisfinazzo/jekyll,fulldecent/jekyll,chrisfinazzo/jekyll,jekyll/jekyll,tillgrallert/jekyll,tillgrallert/jekyll,ryanshaw/jekyll,tillgrallert/jekyll,ryanshaw/jekyll,x-way/jekyll