diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -12,6 +12,7 @@ demandload(globals(), "os re sys signal 
 demandload(globals(), "fancyopts ui hg util lock revlog templater bundlerepo")
 demandload(globals(), "fnmatch hgweb mdiff random signal tempfile time")
 demandload(globals(), "traceback errno socket version struct atexit sets bz2")
+demandload(globals(), "changegroup")
 
 class UnknownCommand(Exception):
     """Exception raised if command is not in the command table."""
@@ -306,11 +307,17 @@ def write_bundle(cg, filename=None, comp
         else:
             fh.write("HG10UN")
             z = nocompress()
-        while 1:
-            chunk = cg.read(4096)
-            if not chunk:
-                break
-            fh.write(z.compress(chunk))
+        # parse the changegroup data, otherwise we will block
+        # in case of sshrepo because we don't know the end of the stream
+
+        # an empty chunkiter is the end of the changegroup
+        empty = False
+        while not empty:
+            empty = True
+            for chunk in changegroup.chunkiter(cg):
+                empty = False
+                fh.write(z.compress(changegroup.genchunk(chunk)))
+            fh.write(z.compress(changegroup.closechunk()))
         fh.write(z.flush())
         cleanup = None
         return filename