--- a/mercurial/bundle2.py	Tue Apr 01 17:59:06 2014 -0500
+++ b/mercurial/bundle2.py	Wed Mar 19 23:36:15 2014 -0700
@@ -89,8 +89,13 @@
 
 :payload:
 
-    The current payload is a 32bit integer with a value of 0. This is
-    considered an "empty" payload.
+    payload is a series of `<chunksize><chunkdata>`.
+
+    `chunksize` is a 32 bits integer, `chunkdata` are plain bytes (as much as
+    `chunksize` says)` The payload part is concluded by a zero size chunk.
+
+    The current implementation always produces either zero or one chunk.
+    This is an implementation limitation that will ultimatly be lifted.
 """
 
 import util
@@ -109,6 +114,7 @@
 _fstreamparamsize = '>H'
 _fpartheadersize = '>H'
 _fparttypesize = '>B'
+_fpayloadsize = '>I'
 
 class bundle20(object):
     """represent an outgoing bundle2 container
@@ -257,12 +263,18 @@
         typesize = _unpack(_fparttypesize, fromheader(1))[0]
         parttype = fromheader(typesize)
         self.ui.debug('part type: "%s"\n' % parttype)
-        current = part(parttype)
         assert fromheader(2) == '\0\0' # no option for now
         del self._offset # clean up layer, nobody saw anything.
         self.ui.debug('part parameters: 0\n')
-        assert self._readexact(4) == '\0\0\0\0' #empty payload
-        self.ui.debug('payload chunk size: 0\n')
+        payload = []
+        payloadsize = self._unpack(_fpayloadsize)[0]
+        self.ui.debug('payload chunk size: %i\n' % payloadsize)
+        while payloadsize:
+            payload.append(self._readexact(payloadsize))
+            payloadsize = self._unpack(_fpayloadsize)[0]
+            self.ui.debug('payload chunk size: %i\n' % payloadsize)
+        payload = ''.join(payload)
+        current = part(parttype, data=payload)
         return current
 
 
@@ -286,7 +298,12 @@
         headerchunk = ''.join(header)
         yield _pack(_fpartheadersize, len(headerchunk))
         yield headerchunk
-        # force empty part for now
-        yield '\0\0\0\0'
+        # we only support fixed size data now.
+        # This will be improved in the future.
+        if len(self.data):
+            yield _pack(_fpayloadsize, len(self.data))
+            yield self.data
+        # end of payload
+        yield _pack(_fpayloadsize, 0)
 
 

--- a/tests/test-bundle2.t	Tue Apr 01 17:59:06 2014 -0500
+++ b/tests/test-bundle2.t	Wed Mar 19 23:36:15 2014 -0700
@@ -15,6 +15,11 @@
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > 
+  > ELEPHANTSSONG = """Patali Dirapata, Cromda Cromda Ripalo, Pata Pata, Ko Ko Ko
+  > Bokoro Dipoulito, Rondi Rondi Pepino, Pata Pata, Ko Ko Ko
+  > Emana Karassoli, Loucra Loucra Ponponto, Pata Pata, Ko Ko Ko."""
+  > assert len(ELEPHANTSSONG) == 178 # future test say 178 bytes, trust it.
+  > 
   > @command('bundle2',
   >          [('', 'param', [], 'stream level parameter'),
   >           ('', 'parts', False, 'include some arbitrary parts to the bundle'),],
@@ -35,6 +40,8 @@
   >        # add a second one to make sure we handle multiple parts
   >        part = bundle2.part('test:empty')
   >        bundler.addpart(part)
+  >        part = bundle2.part('test:song', data=ELEPHANTSSONG)
+  >        bundler.addpart(part)
   > 
   >     if path is None:
   >        file = sys.stdout
@@ -62,6 +69,7 @@
   >     ui.write('parts count:   %i\n' % len(parts))
   >     for p in parts:
   >         ui.write('  :%s:\n' % p.type)
+  >         ui.write('    payload: %i bytes\n' % len(p.data))
   > EOF
   $ cat >> $HGRCPATH << EOF
   > [extensions]
@@ -238,19 +246,26 @@
   start of parts
   bundle part: "test:empty"
   bundle part: "test:empty"
+  bundle part: "test:song"
   end of bundle
 
   $ cat ../parts.hg2
   HG20\x00\x00\x00\r (esc)
   test:empty\x00\x00\x00\x00\x00\x00\x00\r (esc)
-  test:empty\x00\x00\x00\x00\x00\x00\x00\x00 (no-eol) (esc)
+  test:empty\x00\x00\x00\x00\x00\x00\x00\x0c	test:song\x00\x00\x00\x00\x00\xb2Patali Dirapata, Cromda Cromda Ripalo, Pata Pata, Ko Ko Ko (esc)
+  Bokoro Dipoulito, Rondi Rondi Pepino, Pata Pata, Ko Ko Ko
+  Emana Karassoli, Loucra Loucra Ponponto, Pata Pata, Ko Ko Ko.\x00\x00\x00\x00\x00\x00 (no-eol) (esc)
 
 
   $ hg unbundle2 < ../parts.hg2
   options count: 0
-  parts count:   2
+  parts count:   3
+    :test:empty:
+      payload: 0 bytes
     :test:empty:
-    :test:empty:
+      payload: 0 bytes
+    :test:song:
+      payload: 178 bytes
 
   $ hg unbundle2 --debug < ../parts.hg2
   start processing of HG20 stream
@@ -265,8 +280,17 @@
   part type: "test:empty"
   part parameters: 0
   payload chunk size: 0
+  part header size: 12
+  part type: "test:song"
+  part parameters: 0
+  payload chunk size: 178
+  payload chunk size: 0
   part header size: 0
   end of bundle2 stream
-  parts count:   2
+  parts count:   3
+    :test:empty:
+      payload: 0 bytes
     :test:empty:
-    :test:empty:
+      payload: 0 bytes
+    :test:song:
+      payload: 178 bytes