diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -442,12 +442,7 @@ class localrepository(repo.repository):
 
     def lookup(self, key):
         if key == '.':
-            key, second = self.dirstate.parents()
-            if key == nullid:
-                raise repo.RepoError(_("no revision checked out"))
-            if second != nullid:
-                self.ui.warn(_("warning: working directory has two parents, "
-                               "tag '.' uses the first\n"))
+            return self.dirstate.parents()[0]
         elif key == 'null':
             return nullid
         n = self.changelog._match(key)
diff --git a/tests/test-log.out b/tests/test-log.out
--- a/tests/test-log.out
+++ b/tests/test-log.out
@@ -150,7 +150,6 @@ 2 files updated, 0 files merged, 1 files
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 (branch merge, don't forget to commit)
 % log -r . with two parents
-warning: working directory has two parents, tag '.' uses the first
 changeset:   3:e62f78d544b4
 parent:      1:3d5bf5654eda
 user:        test
diff --git a/tests/test-merge-remove.out b/tests/test-merge-remove.out
--- a/tests/test-merge-remove.out
+++ b/tests/test-merge-remove.out
@@ -23,7 +23,6 @@ M bar
 M foo1
   foo
 % reverting foo1 and bar
-warning: working directory has two parents, tag '.' uses the first
 saving current version of bar as bar.orig
 reverting bar
 saving current version of foo1 as foo1.orig