patchbomb: save introductory message in .hg/last-email.txt

hgext/patchbomb.py

@@ -193,6 +193,9 b' def patchbomb(ui, repo, *revs, **opts):'
     PAGER environment variable is set, your pager will be fired up once
     for each patchbomb message, so you can verify everything is alright.
 
+    In case email sending fails, you will find a backup of your series
+    introductory message in ``.hg/last-email.txt``.
+
     Examples::
 
       hg email -r 3000          # send patch 3000 only
@@ -309,6 +312,10 b' def patchbomb(ui, repo, *revs, **opts):'
             ui.write(_('\nWrite the introductory message for the '
                        'patch series.\n\n'))
             body = ui.edit(body, sender)
+            # Save serie description in case sendmail fails
+            msgfile = repo.opener('last-email.txt', 'wb')
+            msgfile.write(body)
+            msgfile.close()
         return body
 
     def getpatchmsgs(patches, patchnames=None):

tests/test-patchbomb.t

@@ -145,6 +145,17 b''
   +b
   
 
+.hg/last-email.txt
+
+  $ cat > editor << '__EOF__'
+  > #!/bin/sh
+  > echo "a precious introductory message" > "$1"
+  > __EOF__
+  $ chmod +x editor
+  $ HGEDITOR="'`pwd`'"/editor hg email -n -t foo -s test -r 0:tip > /dev/null
+  $ cat .hg/last-email.txt
+  a precious introductory message
+
   $ hg email -m test.mbox -f quux -t foo -c bar -s test 0:tip \
   > --config extensions.progress= --config progress.assume-tty=1 \
   > --config progress.delay=0 --config progress.refresh=0