fix patchbomb prompt when sending series of patches

hgext/patchbomb.py

@@ -76,9 +76,11 b' from mercurial import cmdutil, commands,'
 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 b' def patchbomb(ui, repo, *revs, **opts):'
                 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'):

tests/test-patchbomb

@@ -152,6 +152,9 b" hg email --date '1970-1-1 0:1' -n -f quu"
 hg email --date '1970-1-1 0:1' -n -f quux -t foo -c bar --in-reply-to baz \
   -r 0:1 | fixheaders
 
+hg email --date '1970-1-1 0:1' -n -f quux -t foo -c bar --in-reply-to baz \
+  -s test -r 0:1 | fixheaders
+
 echo "% test single flag for single patch"
 hg email --date '1970-1-1 0:1' -n --flag fooFlag -f quux -t foo -c bar -s test \
   -r 2 | fixheaders

tests/test-patchbomb.out

@@ -1177,17 +1177,20 b' diff -r eae5fcf795ee -r e317db6a6f28 .hg'
 +ff2c9fa2018b15fa74b33363bda9527323e2a99f two
 +ff2c9fa2018b15fa74b33363bda9527323e2a99f two.diff
 
+abort: Subject:[PATCH 0 of 2] Please enter a valid value
+This patch series consists of 2 patches.
+
 This patch series consists of 2 patches.
 
 
 Write the introductory message for the patch series.
 
 
-Displaying [PATCH 0 of 2] None ...
+Displaying [PATCH 0 of 2] test ...
 Content-Type: text/plain; charset="us-ascii"
 MIME-Version: 1.0
 Content-Transfer-Encoding: 7bit
-Subject: [PATCH 0 of 2] None
+Subject: [PATCH 0 of 2] test
 Message-Id: <patchbomb.60@
 In-Reply-To: <baz>
 References: <baz>