If a git repository is non-bare, and core.worktree is not set, git
tries to deduce the worktree. This deduction is not always helpful, e.g.
% git --git-dir=$HOME/.nmbug clean -f
would likely delete most of the files in the current directory
$repository, $tempwork) == 0
or die "'git clone' exited with nonzero value\n";
git ('config', '--unset', 'core.worktree');
$repository, $tempwork) == 0
or die "'git clone' exited with nonzero value\n";
git ('config', '--unset', 'core.worktree');
+ git ('config', 'core.bare', 'true');