}
if (rev == null)
return null;
tree = rw.parseTree(rev);
if (i == revChars.length - 1)
return tree.copy();
TreeWalk tw = TreeWalk.forPath(rw.getObjectReader(),
new String(revChars, i + 1, revChars.length - i - 1),
tree);
return tw != null ? tw.getObjectId(0) : null;