fix: fix chained provision in Windows

This commit changes the way in which worktrees
are generated in Windows. In Windows, every provisioned
worktree will have a git config setting that identifies
it as a worktree and holds the source of the worktree.

Further provision calls, i.e. chained provision calls,
in this worktree will use the original source as
provision source.

This is necessary because `git worktree` does not work
together with `git annex` on a crippled file systems, which
means it does not work on most Windows systems.

datalad_remake/commands/provision_cmd.py

@@ -216,9 +216,16 @@ def provide(
     lgr.debug('Provisioning dataset %s at %s', dataset, resolved_worktree_dir)
 
     if on_windows:
+        # Check whether we are already in a provisioned worktree. If that is the
+        # case, we have to provision from the original source.
+        source = dataset.config.get('datalad.make.provision-source', None)
+        if not source:
+            source = dataset.path
         # Create a worktree via `git clone` and check out the requested commit
-        args = ['clone', '.', str(resolved_worktree_dir)]
+        args = ['clone', source, str(resolved_worktree_dir)]
         call_git_lines(args, cwd=dataset.pathobj)
+        args = ['config', '--add', 'datalad.make.provision-source', source]
+        call_git_lines(args, cwd=resolved_worktree_dir)
         if source_branch:
             args = ['checkout', source_branch]
             call_git_lines(args, cwd=resolved_worktree_dir)