Re: [PATCH 2/2] sh-setup: make require_clean_work_tree() work on orphan branches

> git-sh-setup's require_clean_work_tree() always exits with error on an
> orphan branch, even when the index and worktree are both clean.  The
> reason is that require_clean_work_tree() starts off with verifying
> HEAD, to make sure that it can safely pass HEAD to 'git diff-index'
> later when it comes to checking the cleanness of the index, and errors
> out finding the invalid HEAD of the orphan branch.
> 
> There are scripts requiring a clean worktree that should work on an
> orphan branch as well, and those should be able to use this function
> instead of duplicating its functionality and nice error reporting in a
> way that handles orphan branches.
> 
> Fixing this is easy: the index should be compared to the empty tree
> while on an orphan branch, and to HEAD otherwise.
> 
> However, just fixing require_clean_work_tree() this way is also
> dangerous, because scripts must take care to work properly on orphan
> branches.  Currently a script calling require_clean_work_tree() would
> exit on a clean orphan branch, but with the simple fix it would
> continue executing and who knows what the consequences might be if
> the script is not prepared for orphan branches.