[PATCH 1 of 4] revlog: generate full revisions when parent node is missing

[Vishakh H]

# HG changeset patch
# User Vishakh H <vsh426 at gmail.com>
# Date 1281708711 -19800
# Node ID f529cea7638f4d0dce2c9ea695c0b69521266c8a
# Parent  7fa36341e7a01a637f397673a11d09241cda8c7a
revlog: generate full revisions when parent node is missing

The full revision is sent if the first parent, against which diff is calculated, is
missing at remote. This happens in the case of shallow clones.

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1172,15 +1172,19 @@
             self._cache = (node, curr, text)
         return node
 
-    def group(self, nodelist, lookup, infocollect=None):
+    def group(self, nodelist, lookup, infocollect=None, fullrev=False):
         """Calculate a delta group, yielding a sequence of changegroup chunks
         (strings).
 
         Given a list of changeset revs, return a set of deltas and
-        metadata corresponding to nodes. the first delta is
-        parent(nodes[0]) -> nodes[0] the receiver is guaranteed to
-        have this parent as it has all history before these
-        changesets. parent is parent[0]
+        metadata corresponding to nodes. The first delta is
+        first parent(nodelist[0]) -> nodelist[0], the receiver is
+        guaranteed to have this parent as it has all history before
+        these changesets. In the case firstparent is nullrev the
+        changegroup starts with a full revision.
+        fullrev forces the insertion of the full revision, necessary
+        in the case of shallow clones where the first parent might
+        not exist at the reciever.
         """
 
         revs = [self.rev(n) for n in nodelist]
@@ -1193,6 +1197,8 @@
         # add the parent of the first rev
         p = self.parentrevs(revs[0])[0]
         revs.insert(0, p)
+        if p == nullrev:
+            fullrev = True
 
         # build deltas
         for d in xrange(len(revs) - 1):
@@ -1204,9 +1210,10 @@
 
             p = self.parents(nb)
             meta = nb + p[0] + p[1] + lookup(nb)
-            if a == -1:
+            if fullrev:
                 d = self.revision(nb)
                 meta += mdiff.trivialdiffheader(len(d))
+                fullrev = False
             else:
                 d = self.revdiff(a, b)
             yield changegroup.chunkheader(len(meta) + len(d))