qnew: use "editor" argument of "commit()" instead of explicit "ui.edit()"

Before this patch, "hg qnew" invokes "ui.edit()" explicitly to get
commit message edited manually.

This requires explicit "localrepository.savecommitmessage()"
invocation to save edited commit message into ".hg/last-message.txt",
because unexpected exception raising may abort command execution
before saving it in "localrepository.commit()".

This patch uses "editor" argument of "localrepository.commit()"
instead of explicit "ui.edit()" invocation for "hg qnew".

"localrepository.commit()" will invoke "desceditor()" function newly
added by this patch, and save edited commit message into
".hg/last-message.txt" automatically.

This patch passes not "editor" but "desceditor" to "commit()", because
"hg qnew" requires editor function to return edited message if not
empty, or default message otherwise.

This patch applies "rstrip()" on "defaultmsg" at comparison between
"nctx.description()" and "defaultmsg", because the former should be
stripped by "changelog.stripdesc()" and the latter may have tail white
spaces inherited from "patchfn".

hgext/mq.py

@@ -1026,6 +1026,7 b' class queue(object):'
            msg: a string or a no-argument function returning a string
         """
         msg = opts.get('msg')
+        editor = opts.get('editor')
         user = opts.get('user')
         date = opts.get('date')
         if date:
@@ -1078,12 +1079,23 b' class queue(object):'
                         p.write("# User " + user + "\n")
                     if date:
                         p.write("# Date %s %s\n\n" % date)
-                if util.safehasattr(msg, '__call__'):
-                    msg = msg()
-                    repo.savecommitmessage(msg)
-                commitmsg = msg and msg or ("[mq]: %s" % patchfn)
+
+                defaultmsg = "[mq]: %s" % patchfn
+                if editor:
+                    origeditor = editor
+                    def desceditor(repo, ctx, subs):
+                        desc = origeditor(repo, ctx, subs)
+                        if desc.rstrip():
+                            return desc
+                        else:
+                            return defaultmsg
+                    commitmsg = msg
+                    editor = desceditor
+                else:
+                    commitmsg = msg or defaultmsg
+
                 n = newcommit(repo, None, commitmsg, user, date, match=match,
-                              force=True)
+                              force=True, editor=editor)
                 if n is None:
                     raise util.Abort(_("repo commit failed"))
                 try:
@@ -1092,8 +1104,9 b' class queue(object):'
                     self.parseseries()
                     self.seriesdirty = True
                     self.applieddirty = True
-                    if msg:
-                        msg = msg + "\n\n"
+                    nctx = repo[n]
+                    if nctx.description() != defaultmsg.rstrip():
+                        msg = nctx.description() + "\n\n"
                         p.write(msg)
                     if commitfiles:
                         parent = self.qparents(repo, n)
@@ -2417,14 +2430,12 b' def new(ui, repo, patch, *args, **opts):'
     Returns 0 on successful creation of a new patch.
     """
     msg = cmdutil.logmessage(ui, opts)
-    def getmsg():
-        return ui.edit(msg, opts.get('user') or ui.username())
     q = repo.mq
     opts['msg'] = msg
     if opts.get('edit'):
-        opts['msg'] = getmsg
-    else:
-        opts['msg'] = msg
+        def editor(repo, ctx, subs):
+            return ui.edit(ctx.description() + "\n", ctx.user())
+        opts['editor'] = editor
     setupheaderopts(ui, opts)
     q.new(repo, patch, *args, **opts)
     q.savedirty()

tests/test-mq-qnew.t

@@ -247,8 +247,9 b' Test saving last-message.txt'
   >             raise util.Abort('emulating unexpected abort')
   >     repo.__class__ = commitfailure
   > EOF
-  $ cat > .hg/hgrc <<EOF
+  $ cat >> .hg/hgrc <<EOF
   > [extensions]
+  > # this failure occurs before editor invocation
   > commitfailure = $TESTTMP/commitfailure.py
   > EOF
 
@@ -259,13 +260,62 b' Test saving last-message.txt'
   > echo "test saving last-message.txt" >> \$1
   > EOF
 
+(test that editor is not invoked before transaction starting)
+
+  $ rm -f .hg/last-message.txt
+  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qnew -e patch
+  abort: emulating unexpected abort
+  [255]
+  $ cat .hg/last-message.txt
+  cat: .hg/last-message.txt: No such file or directory
+  [1]
+
+(test that editor is invoked and commit message is saved into
+"last-message.txt")
+
+  $ cat >> .hg/hgrc <<EOF
+  > [extensions]
+  > commitfailure = !
+  > [hooks]
+  > # this failure occurs after editor invocation
+  > pretxncommit.unexpectedabort = false
+  > EOF
+
   $ rm -f .hg/last-message.txt
   $ HGEDITOR="sh $TESTTMP/editor.sh" hg qnew -e patch
   ==== before editing
+  
   ====
-  abort: emulating unexpected abort
+  transaction abort!
+  rollback completed
+  note: commit message saved in .hg/last-message.txt
+  abort: pretxncommit.unexpectedabort hook exited with status 1
   [255]
   $ cat .hg/last-message.txt
+  
   test saving last-message.txt
 
+  $ cat >> .hg/hgrc <<EOF
+  > [hooks]
+  > pretxncommit.unexpectedabort =
+  > EOF
+
+Test handling default message with the patch filename with tail whitespaces
+
+  $ cat > $TESTTMP/editor.sh << EOF
+  > echo "==== before editing"
+  > cat \$1
+  > echo "===="
+  > echo "[mq]: patch        " > \$1
+  > EOF
+
+  $ rm -f .hg/last-message.txt
+  $ HGEDITOR="sh $TESTTMP/editor.sh" hg qnew -e "patch "
+  ==== before editing
+  
+  ====
+  $ cat ".hg/patches/patch "
+  # HG changeset patch
+  # Parent 0000000000000000000000000000000000000000
+
   $ cd ..