bork doesn't work on bash 4.4.12 on Arch Linux because of syntax error:
$ bats test
...
✗ bag: pop removes top item from stack
(from function `bag' in file lib/helpers/bag.sh, line 27,
in test file test/help-bag.bats, line 40)
`bag pop foo' failed
/media/sf_bork/lib/helpers/bag.sh: 27 行: unset: `foo[1]=': 有効な識別子ではありません
...
bork doesn't work on bash 4.4.12 on Arch Linux because of syntax error:
This PR fix it.