diff -r 9f45d3d526f9 -r 32338e27bb9d mercurial/localrepo.py
--- a/mercurial/localrepo.py	Mon Mar 11 01:10:20 2019 +0100
+++ b/mercurial/localrepo.py	Mon Mar 11 02:35:18 2019 +0100
@@ -2132,6 +2132,8 @@
             for ctx in self['.'].parents():
                 ctx.manifest()  # accessing the manifest is enough
 
+            # accessing fnode cache warms the cache
+            tagsmod.fnoderevs(self.ui, unfi, unfi.changelog.revs())
             # accessing tags warm the cache
             self.tags()
             self.filtered('served').tags()