copies: remove checkdirs options

This removes the undocumented merge.followdirs option, which has
always been true.

mercurial/copies.py

@@ -174,7 +174,7 b' def pathcopies(x, y):'
         return _backwardcopies(x, y)
     return _chain(x, y, _backwardcopies(x, a), _forwardcopies(a, y))
 
-def mergecopies(repo, c1, c2, ca, checkdirs=True):
+def mergecopies(repo, c1, c2, ca):
     """
     Find moves and copies between context c1 and c2 that are relevant
     for merging.
@@ -310,7 +310,7 b' def mergecopies(repo, c1, c2, ca, checkd'
             repo.ui.debug("   %s -> %s %s\n" % (f, fullcopy[f], note))
     del diverge2
 
-    if not fullcopy or not checkdirs:
+    if not fullcopy:
         return copy, diverge
 
     repo.ui.debug("  checking for directory renames\n")

mercurial/merge.py

@@ -188,8 +188,7 b' def manifestmerge(repo, p1, p2, pa, over'
     elif pa == p2: # backwards
         pa = p1.p1()
     elif pa and repo.ui.configbool("merge", "followcopies", True):
-        dirs = repo.ui.configbool("merge", "followdirs", True)
-        copy, diverge = copies.mergecopies(repo, p1, p2, pa, dirs)
+        copy, diverge = copies.mergecopies(repo, p1, p2, pa)
         for of, fl in diverge.iteritems():
             act("divergent renames", "dr", of, fl)