patchbomb: treat empty address list as no addresses

Previously it wasn't possible to use configuration to avoid
being prompted for e.g. a CC list when using patchbomb to send
emails.

We now make it possible to supply an empty value.

hgext/patchbomb.py

@@ -44,6 +44,13 b' that the patchbomb extension can automat'
 directly from the commandline. See the [email] and [smtp] sections in
 hgrc(5) for details.
 
+By default, :hg:`email` will prompt for a ``To`` or ``CC`` header if
+you do not supply one via configuration or the command line.  You can
+override this to never prompt by configuring an empty value::
+
+  [email]
+  cc =
+
 You can control the default inclusion of an introduction message with the
 ``patchbomb.intro`` configuration option. The configuration is always
 overwritten by command line flags like --intro and --desc::
@@ -596,10 +603,12 b' def email(ui, repo, *revs, **opts):'
 
         # not on the command line: fallback to config and then maybe ask
         addr = (ui.config('email', configkey) or
-                ui.config('patchbomb', configkey) or
-                '')
-        if not addr and ask:
-            addr = prompt(ui, header, default=default)
+                ui.config('patchbomb', configkey))
+        if not addr:
+            specified = (ui.hasconfig('email', configkey) or
+                         ui.hasconfig('patchbomb', configkey))
+            if not specified and ask:
+                addr = prompt(ui, header, default=default)
         if addr:
             showaddrs.append('%s: %s' % (header, addr))
             return mail.addrlistencode(ui, [addr], _charsets, opts.get('test'))

tests/test-patchbomb.t

@@ -2682,13 +2682,17 b' test outgoing:'
   +d
   
 
+Don't prompt for a CC header.
+
+  $ echo "[email]" >> $HGRCPATH
+  $ echo "cc=" >> $HGRCPATH
+
 dest#branch URIs:
   $ hg email --date '1980-1-1 0:1' -n -t foo -s test -o ../t#test
   comparing with ../t
   From [test]: test
   this patch series consists of 1 patches.
   
-  Cc: 
   
   displaying [PATCH] test ...
   Content-Type: text/plain; charset="us-ascii"
@@ -2854,7 +2858,6 b' single rev'
   @@ -1,1 +1,2 @@
    d
   +d
-  Cc: 
   
   sending [PATCH] test ...
   sending mail: $TESTTMP/t2/pretendmail.sh -f test foo