--- a/mercurial/store.py	Mon Mar 18 14:57:43 2019 +0300
+++ b/mercurial/store.py	Mon Mar 18 16:56:24 2019 +0300
@@ -481,6 +481,8 @@
                 # chunksize, so let's keep iterating
                 pass
 
+        if chunk:
+            raise error.Abort(_("fncache does not ends with a newline"))
         self._checkentries(fp)
         fp.close()