diff --git a/mercurial/bundlerepo.py b/mercurial/bundlerepo.py
--- a/mercurial/bundlerepo.py
+++ b/mercurial/bundlerepo.py
@@ -15,7 +15,7 @@ from node import nullid
 from i18n import _
 import os, tempfile, shutil
 import changegroup, util, mdiff, discovery, cmdutil, scmutil, exchange
-import localrepo, changelog, manifest, filelog, revlog, error
+import localrepo, changelog, manifest, filelog, revlog, error, phases
 
 class bundlerevlog(revlog.revlog):
     def __init__(self, opener, indexfile, bundle, linkmapper):
@@ -184,6 +184,23 @@ class bundlepeer(localrepo.localpeer):
     def canpush(self):
         return False
 
+class bundlephasecache(phases.phasecache):
+    def __init__(self, *args, **kwargs):
+        super(bundlephasecache, self).__init__(*args, **kwargs)
+        if util.safehasattr(self, 'opener'):
+            self.opener = scmutil.readonlyvfs(self.opener)
+
+    def write(self):
+        raise NotImplementedError
+
+    def _write(self, fp):
+        raise NotImplementedError
+
+    def _updateroots(self, phase, newroots, tr):
+        self.phaseroots[phase] = newroots
+        self.invalidate()
+        self.dirty = True
+
 class bundlerepository(localrepo.localrepository):
     def __init__(self, ui, path, bundlename):
         self._tempparent = None
@@ -226,6 +243,10 @@ class bundlerepository(localrepo.localre
         self.bundlefilespos = {}
 
     @localrepo.unfilteredpropertycache
+    def _phasecache(self):
+        return bundlephasecache(self, self._phasedefaults)
+
+    @localrepo.unfilteredpropertycache
     def changelog(self):
         # consume the header if it exists
         self.bundle.changelogheader()
diff --git a/mercurial/phases.py b/mercurial/phases.py
--- a/mercurial/phases.py
+++ b/mercurial/phases.py
@@ -161,7 +161,7 @@ class phasecache(object):
     def copy(self):
         # Shallow copy meant to ensure isolation in
         # advance/retractboundary(), nothing more.
-        ph = phasecache(None, None, _load=False)
+        ph = self.__class__(None, None, _load=False)
         ph.phaseroots = self.phaseroots[:]
         ph.dirty = self.dirty
         ph.opener = self.opener