--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -221,8 +221,6 @@ def update(repo, node):
     """update the working directory to node, merging linear changes"""
     stats = _merge.update(repo, node, False, False, None, None)
     _showstats(repo, stats)
-    branch = repo.changectx(node).branch()
-    repo.opener("branch", "w").write(branch + "\n")
     if stats[3]:
         repo.ui.status(_("There are unresolved merges with"
                          " locally modified files.\n"))
@@ -231,8 +229,6 @@ def update(repo, node):
 def clean(repo, node, wlock=None, show_stats=True):
     """forcibly switch the working directory to node, clobbering changes"""
     stats = _merge.update(repo, node, False, True, None, wlock)
-    branch = repo.changectx(node).branch()
-    repo.opener("branch", "w").write(branch + "\n")
     if show_stats: _showstats(repo, stats)
     return stats[3]