diff --git a/mercurial/chgserver.py b/mercurial/chgserver.py
--- a/mercurial/chgserver.py
+++ b/mercurial/chgserver.py
@@ -147,9 +147,14 @@
     """
     def trystat(path):
         try:
-            st = os.stat(path)
-            return (st.st_mtime, st.st_size)
-        except OSError:
+            # sometimes __version__.py may change without stat change
+            # (issue5653), check its content instead.
+            if '__version__' in path:
+                return util.readfile(path)
+            else:
+                st = os.stat(path)
+                return (st.st_mtime, st.st_size)
+        except (OSError, IOError):
             # could be ENOENT, EPERM etc. not fatal in any case
             pass
     return _hashlist(map(trystat, paths))[:12]