copies: remove hack for adding root dir to util.dirs object

Differential Revision: https://phab.mercurial-scm.org/D6404

mercurial/copies.py

@@ -588,9 +588,6 b' def _fullcopytracing(repo, c1, c2, base)'
 
     # generate a directory move map
     d1, d2 = c1.dirs(), c2.dirs()
-    # Hack for adding '', which is not otherwise added, to d1 and d2
-    d1.addpath('/')
-    d2.addpath('/')
     invalid = set()
     dirmove = {}