update: specify custom conflict markers for update (BC)

Add custom conflict markers 'working copy' and 'destination' for doing hg update
when there are conflicts between your working copy and the destination.

mercurial/hg.py

@@ -483,7 +483,8 b' def updaterepo(repo, node, overwrite):'
     When overwrite is set, changes are clobbered, merged else
 
     returns stats (see pydoc mercurial.merge.applyupdates)"""
-    return mergemod.update(repo, node, False, overwrite, None)
+    return mergemod.update(repo, node, False, overwrite, None,
+                           labels=['working copy', 'destination'])
 
 def update(repo, node):
     """update the working directory to node, merging linear changes"""

tests/test-merge-revert2.t

@@ -57,11 +57,11 b''
   @@ -1,3 +1,7 @@
    added file1
    another line of text
-  +<<<<<<< local: c3fa057dd86f  - test: "added file1 and file2"
+  +<<<<<<< working copy: c3fa057dd86f  - test: "added file1 and file2"
   +changed file1 different
   +=======
    changed file1
-  +>>>>>>> other: dfab7f3c2efb - test: "changed file1"
+  +>>>>>>> destination:  dfab7f3c2efb - test: "changed file1"
 
   $ hg status
   M file1