Make diffstat optional for patchbomb script.

contrib/patchbomb

@@ -192,6 +192,7 b' def patchbomb(ui, repo, *revs, **opts):'
 
     ui.write('\n')
 
+    if opts['diffstat']:
     d = cdiffstat('Final summary:\n', jumbo)
     if d: msg.attach(MIMEText(d))