bundlerepo: don't insert index tuples with full nodes as linkrev

The index format has a documented format and latter changes will start
to enforce the field types. The bundlerepo uses full nodes for the
linkrev field when it should be using revision numbers. Use the link
mapping to resolve them, except in the special case of self-references.
Those are actually indications of a missing linkrev.

Differential Revision: https://phab.mercurial-scm.org/D9160

mercurial/bundlerepo.py

@@ -63,11 +63,14 b' class bundlerevlog(revlog.revlog):'
             size = len(delta)
             start = cgunpacker.tell() - size
 
-            link = linkmapper(cs)
             if self.index.has_node(node):
                 # this can happen if two branches make the same change
                 self.bundlerevs.add(self.index.rev(node))
                 continue
+            if cs == node:
+                linkrev = nullrev
+            else:
+                linkrev = linkmapper(cs)
 
             for p in (p1, p2):
                 if not self.index.has_node(p):
@@ -87,7 +90,7 b' class bundlerevlog(revlog.revlog):'
                 size,
                 -1,
                 baserev,
-                link,
+                linkrev,
                 self.rev(p1),
                 self.rev(p2),
                 node,