patchbomb: --desc implies --intro

For a single patch, an introductory text should not remain unsent
if --intro has been omitted, as the intent of --desc is clear.

hgext/patchbomb.py

@@ -105,6 +105,10 b' def cdiffstat(ui, summary, patchlines):'
         raise util.Abort(_('diffstat rejected'))
     return s
 
+def introneeded(opts, number):
+    '''is an introductory message required?'''
+    return number > 1 or opts.get('intro') or opts.get('desc')
+
 def makepatch(ui, repo, patch, opts, _charsets, idx, total, patchname=None):
 
     desc = []
@@ -170,7 +174,7 b' def makepatch(ui, repo, patch, opts, _ch'
         flag = ' ' + flag
 
     subj = desc[0].strip().rstrip('. ')
-    if total == 1 and not opts.get('intro'):
+    if not introneeded(opts, total):
         subj = '[PATCH%s] %s' % (flag, opts.get('subject') or subj)
     else:
         tlen = len(str(total))
@@ -329,7 +333,7 b' def patchbomb(ui, repo, *revs, **opts):'
                             len(patches), name)
             msgs.append(msg)
 
-        if len(patches) > 1 or opts.get('intro'):
+        if introneeded(opts, len(patches)):
             tlen = len(str(len(patches)))
 
             flag = ' '.join(opts.get('flag'))

tests/test-patchbomb

@@ -126,6 +126,11 b' echo "% test intro for single patch"'
 hg email --date '1970-1-1 0:1' -n --intro -f quux -t foo -c bar -s test \
   -r 2 | fixheaders
 
+echo "% test --desc without --intro for a single patch"
+echo foo > intro.text
+hg email --date '1970-1-1 0:1' -n --desc intro.text -f quux -t foo -c bar \
+  -s test -r 2 | fixheaders
+
 echo "% test intro for multiple patches"
 hg email --date '1970-1-1 0:1' -n --intro -f quux -t foo -c bar -s test \
   -r 0:1 | fixheaders

tests/test-patchbomb.out

@@ -940,6 +940,52 b' diff -r 97d72e5f12c7 -r ff2c9fa2018b c'
 @@ -0,0 +1,1 @@
 +c
 
+% test --desc without --intro for a single patch
+This patch series consists of 1 patches.
+
+
+Displaying [PATCH 0 of 1] test ...
+Content-Type: text/plain; charset="us-ascii"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [PATCH 0 of 1] test
+Message-Id: <patchbomb.60@
+User-Agent: Mercurial-patchbomb
+Date: Thu, 01 Jan 1970 00:01:00 +0000
+From: quux
+To: foo
+Cc: bar
+
+foo
+
+Displaying [PATCH 1 of 1] c ...
+Content-Type: text/plain; charset="us-ascii"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [PATCH 1 of 1] c
+X-Mercurial-Node: ff2c9fa2018b15fa74b33363bda9527323e2a99f
+Message-Id: <ff2c9fa2018b15fa74b3.61@
+In-Reply-To: <patchbomb.60@
+References: <patchbomb.60@
+User-Agent: Mercurial-patchbomb
+Date: Thu, 01 Jan 1970 00:01:01 +0000
+From: quux
+To: foo
+Cc: bar
+
+# HG changeset patch
+# User test
+# Date 3 0
+# Node ID ff2c9fa2018b15fa74b33363bda9527323e2a99f
+# Parent  97d72e5f12c7e84f85064aa72e5a297142c36ed9
+c
+
+diff -r 97d72e5f12c7 -r ff2c9fa2018b c
+--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
++++ b/c	Thu Jan 01 00:00:03 1970 +0000
+@@ -0,0 +1,1 @@
++c
+
 % test intro for multiple patches
 This patch series consists of 2 patches.