new file mode 100644
--- /dev/null
+++ b/diff_cmd.py
@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+import re
+
+from mercurial import patch
+
+import util
+import hg_delta_editor
+
+b_re = re.compile(r'^\+\+\+ b\/([^\n]*)', re.MULTILINE)
+a_re = re.compile(r'^--- a\/([^\n]*)', re.MULTILINE)
+devnull_re = re.compile(r'^([-+]{3}) /dev/null', re.MULTILINE)
+header_re = re.compile(r'^diff --git .* b\/(.*)', re.MULTILINE)
+newfile_devnull_re = re.compile(r'^--- /dev/null\n\+\+\+ b/([^\n]*)',
+                                re.MULTILINE)
+def filterdiff(diff, base_revision):
+    diff = newfile_devnull_re.sub(r'--- \1\t(revision 0)' '\n'
+                                  r'+++ \1\t(working copy)',
+                                  diff)
+    diff = a_re.sub(r'--- \1'+ ('\t(revision %d)' % base_revision), diff)
+    diff = b_re.sub(r'+++ \1' + '\t(working copy)', diff)
+    diff = devnull_re.sub(r'\1 /dev/null' '\t(working copy)', diff)
+
+    diff = header_re.sub(r'Index: \1' + '\n' + ('=' * 67), diff)
+    return diff
+
+
+@util.register_subcommand('diff')
+def diff_command(ui, repo, hg_repo_path, **opts):
+    """Show a diff of the most recent revision against its parent from svn.
+    """
+    hge = hg_delta_editor.HgChangeReceiver(hg_repo_path,
+                                           ui_=ui)
+    svn_commit_hashes = dict(zip(hge.revmap.itervalues(),
+                                 hge.revmap.iterkeys()))
+    o_r = util.outgoing_revisions(ui, repo, hge, svn_commit_hashes)
+    parent = repo.parents()[0]
+    if o_r:
+        parent = repo[o_r[-1]].parents()[0]
+    base_rev, _junk = svn_commit_hashes[parent.node()]
+    it = patch.diff(repo, parent.node(), None, 
+                    opts=patch.diffopts(ui, opts))
+    ui.write(filterdiff(''.join(it), base_rev))