patchbomb: add (optional) note to 0 of 0 prompt

hgext/patchbomb.py

@@ -384,7 +384,7 b' def patchbomb(ui, repo, *revs, **opts):'
         prefix = '[PATCH %0*d of %d%s]' % (tlen, 0, len(patches), flag)
 
         subj = (opts.get('subject') or
-                prompt(ui, 'Subject: ', rest=prefix, default=''))
+                prompt(ui, '(optional) Subject: ', rest=prefix, default=''))
         if not subj:
             return None         # skip intro if the user doesn't bother
 

tests/test-patchbomb.t

@@ -1572,7 +1572,7 b' no intro message in non-interactive mode'
   >  -r 0:1
   This patch series consists of 2 patches.
   
-  Subject: [PATCH 0 of 2] 
+  (optional) Subject: [PATCH 0 of 2] 
   
   Displaying [PATCH 1 of 2] a ...
   Content-Type: text/plain; charset="us-ascii"