# HG changeset patch
# User Matt Mackall <mpm@selenic.com>
# Date 1131406824 28800
# Node ID 46a07392cf28ac38bc22e78cc7b764007e337b07
# Parent  b254243b71595549519a558b1e134a6312235480
Add safety check for addgroup



diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -784,6 +784,10 @@ class revlog:
                 continue
             delta = chunk[80:]
 
+            for p in (p1, p2):
+                if not p in self.nodemap:
+                    raise RevlogError(_("unknown parent %s") % short(p1))
+
             if not chain:
                 # retrieve the parent revision of the delta chain
                 chain = p1