--- a/hgext/patchbomb.py	Fri Oct 16 23:57:34 2009 +0200
+++ b/hgext/patchbomb.py	Mon Oct 19 23:27:20 2009 +0300
@@ -76,9 +76,11 @@
 from mercurial.i18n import _
 from mercurial.node import bin
 
-def prompt(ui, prompt, default=None, rest=': ', empty_ok=False):
+def prompt(ui, prompt, default='', rest=': ', empty_ok=False):
     if not ui.interactive():
-        return default
+        if default or empty_ok:
+            return default
+        raise util.Abort(_("%sPlease enter a valid value" % (prompt+rest)))
     if default:
         prompt += ' [%s]' % default
     prompt += rest
@@ -331,8 +333,7 @@
                 subj = '[PATCH %0*d of %d %s] ' % (tlen, 0, len(patches), flag)
             else:
                 subj = '[PATCH %0*d of %d] ' % (tlen, 0, len(patches))
-            subj += opts.get('subject') or prompt(ui, 'Subject:', rest=subj,
-                                                    default='None')
+            subj += opts.get('subject') or prompt(ui, 'Subject:', rest=subj)
 
             body = ''
             if opts.get('diffstat'):