Handle hg under /

mercurial/util.py

@@ -175,6 +175,9 b' def pathto(n1, n2):'
 
 def canonpath(root, cwd, myname):
     """return the canonical path of myname, given cwd and root"""
+    if root == os.sep:
+        rootsep = os.sep
+    else:
     rootsep = root + os.sep
     name = myname
     if not name.startswith(os.sep):