patchbomb: show prompt and selection in non-interactive mode

Akin to 01ada7b1861d for the custom patchbomb prompt.

hgext/patchbomb.py

@@ -81,9 +81,7 b' from mercurial.i18n import _'
 from mercurial.node import bin
 
 def prompt(ui, prompt, default=None, rest=':'):
-    if not ui.interactive():
-        if default is not None:
-            return default
+    if not ui.interactive() and default is None:
         raise util.Abort(_("%s Please enter a valid value" % (prompt + rest)))
     if default:
         prompt += ' [%s]' % default

tests/test-patchbomb.t

@@ -1776,6 +1776,7 b' test multi-byte domain parsing:'
   $ hg email --date '1980-1-1 0:1' -m tmp.mbox -f quux -t "bar@${UUML}nicode.com" -s test -r 0
   This patch series consists of 1 patches.
   
+  Cc: 
   
   Writing [PATCH] test ...
 
@@ -1820,11 +1821,13 b' test outgoing:'
   $ hg email --date '1980-1-1 0:1' -n -t foo -s test -o ../t
   comparing with ../t
   searching for changes
+  From [test]: test
   This patch series consists of 8 patches.
   
   
   Write the introductory message for the patch series.
   
+  Cc: 
   
   Displaying [PATCH 0 of 8] test ...
   Content-Type: text/plain; charset="us-ascii"
@@ -2092,8 +2095,10 b' dest#branch URIs:'
   $ hg email --date '1980-1-1 0:1' -n -t foo -s test -o ../t#test
   comparing with ../t
   searching for changes
+  From [test]: test
   This patch series consists of 1 patches.
   
+  Cc: 
   
   Displaying [PATCH] test ...
   Content-Type: text/plain; charset="us-ascii"