diff -r fbd4ce55bcbd -r 328ca3b9e545 mercurial/statichttprepo.py
--- a/mercurial/statichttprepo.py	Thu Feb 07 21:16:25 2019 -0800
+++ b/mercurial/statichttprepo.py	Mon Jan 21 17:37:33 2019 +0000
@@ -13,6 +13,7 @@
 
 from .i18n import _
 from . import (
+    branchmap,
     changelog,
     error,
     localrepo,
@@ -193,7 +194,7 @@
         self.changelog = changelog.changelog(self.svfs)
         self._tags = None
         self.nodetagscache = None
-        self._branchcaches = {}
+        self._branchcaches = branchmap.BranchMapCache()
         self._revbranchcache = None
         self.encodepats = None
         self.decodepats = None