mercurial/changelog.py

--- a/mercurial/changelog.py	Thu Aug 24 17:44:08 2017 -0700
+++ b/mercurial/changelog.py	Fri Aug 25 22:05:10 2017 -0700
@@ -14,6 +14,7 @@
     bin,
     hex,
     nullid,
+    wdirid,
 )
 
 from . import (
@@ -535,6 +536,9 @@
         # overlay over the standard revlog._addrevision to track the new
         # revision on the transaction.
         rev = len(self)
+        if node == wdirid: # nullid is checked in super method
+            raise error.RevlogError(_("%s: attempt to add wdir revision") %
+                                    (self.indexfile))
         node = super(changelog, self)._addrevision(node, rawtext, transaction,
                                                    *args, **kwargs)
         revs = transaction.changes.get('revs')