diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -779,7 +779,7 @@ def calculateupdates(repo, wctx, mctx, a
                                 branchmerge, force,
                                 partial, acceptremote, followcopies)
 
-    else: # only when merge.preferancestor=* - experimentalish code
+    else: # only when merge.preferancestor=* - the default
         repo.ui.status(
             _("note: merging %s and %s using bids from ancestors %s\n") %
             (wctx, mctx, _(' and ').join(str(anc) for anc in ancestors)))
@@ -1048,7 +1048,7 @@ def update(repo, node, branchmerge, forc
 
         p2 = repo[node]
         if pas[0] is None:
-            if repo.ui.config("merge", "preferancestor") == '*':
+            if repo.ui.config("merge", "preferancestor", '*') == '*':
                 cahs = repo.changelog.commonancestorsheads(p1.node(), p2.node())
                 pas = [repo[anc] for anc in (sorted(cahs) or [nullid])]
             else:
diff --git a/tests/test-merge-criss-cross.t b/tests/test-merge-criss-cross.t
--- a/tests/test-merge-criss-cross.t
+++ b/tests/test-merge-criss-cross.t
@@ -72,7 +72,7 @@ Criss cross merging
      summary:     0 base
   
 
-  $ hg merge -v --debug --tool internal:dump 5
+  $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor='!'
   note: using 0f6b37dbe527 as ancestor of 3b08d01b0ab5 and adfe50279922
         alternatively, use --config merge.preferancestor=40663881a6dd
     searching for copies back to rev 3
@@ -209,13 +209,13 @@ The other way around:
 Verify how the output looks and and how verbose it is:
 
   $ hg up -qC
-  $ hg merge --config merge.preferancestor="*"
+  $ hg merge
   note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ hg up -qC
-  $ hg merge -v --config merge.preferancestor="*"
+  $ hg merge -v
   note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
   
   calculating bids for ancestor 0f6b37dbe527
@@ -288,7 +288,7 @@ http://stackoverflow.com/questions/93500
   $ echo b >> x
   $ hg commit -qm cb
 
-  $ hg merge
+  $ hg merge --config merge.preferancestor='!'
   note: using 70008a2163f6 as ancestor of 0d355fdef312 and 4b8b546a3eef
         alternatively, use --config merge.preferancestor=b211bbc6eb3c
   merging x