Allow word splitting and disable shellcheck SC2086 when using
git-rev-list to build the commit list.

Fixes: 4fd0c6ab1a9e ("Fix most shellcheck warnings in git-arc.sh")

After updating I started getting the following error when doing git arc list main..feature:

fatal: ambiguous argument 'b48029983aecdc79e14ac161b787a13172fe796a
^ba91e31f478aaade96bbdbf01560e8b7cbe41b56': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
git-arc: invalid commit ID main..feature

It seems that git-rev-list expects commits to be listed separately, this patch fixes the above error.