mq: use the editor gotten by "getcommiteditor()" instead of "ui.edit()" (qrefresh/qfold)

This patch also replaces "editor = False" by "editor =
cmdutil.getcommiteditor()", because:

  - it allows to hook commit message determination easily, even in the
    case without "--edit"

  - it avoids regression (or additional care) around saving
    "last-message.txt", even if MQ's "newcommit()" changes its
    implementation logic from "localrepository.commit" to
    "localrepository.commitctx" with "memctx" in the future

    to save commit message into "last-messge.txt" with "memctx",
    "editor" should be valid function.

hgext/mq.py

@@ -1656,17 +1656,18 b' class queue(object):'
                 # might be nice to attempt to roll back strip after this
 
                 defaultmsg = "[mq]: %s" % patchfn
-                editor = False
+                editor = cmdutil.getcommiteditor()
                 if edit:
-                    def desceditor(repo, ctx, subs):
-                        desc = self.ui.edit(ctx.description() + "\n",
-                                            ctx.user())
+                    def finishdesc(desc):
                         if desc.rstrip():
                             ph.setmessage(desc)
                             return desc
                         return defaultmsg
+                    # i18n: this message is shown in editor with "HG: " prefix
+                    extramsg = _('Leave message empty to use default message.')
+                    editor = cmdutil.getcommiteditor(finishdesc=finishdesc,
+                                                     extramsg=extramsg)
                     message = msg or "\n".join(ph.message)
-                    editor = desceditor
                 elif not msg:
                     if not ph.message:
                         message = defaultmsg

tests/test-mq-qfold.t

@@ -20,6 +20,8 b' init:'
   $ hg qnew -f p3
 
 Fold in the middle of the queue:
+(this tests also that editor is not invoked if '--edit' is not
+specified)
 
   $ hg qpop p1
   popping p3
@@ -34,7 +36,7 b' Fold in the middle of the queue:'
    a
   +a
 
-  $ hg qfold p2
+  $ HGEDITOR=cat hg qfold p2
   $ grep git .hg/patches/p1 && echo 'git patch found!'
   [1]
 
@@ -215,6 +217,15 b' Test saving last-message.txt:'
   $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e p3
   ==== before editing
   original message
+  
+  
+  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
+  HG: Leave message empty to use default message.
+  HG: --
+  HG: user: test
+  HG: branch 'default'
+  HG: added aa
+  HG: changed a
   ====
   transaction abort!
   rollback completed
@@ -225,7 +236,26 b' Test saving last-message.txt:'
   $ cat .hg/last-message.txt
   original message
   
+  
+  
   test saving last-message.txt
 
+(confirm whether files listed up in the commit message editing are correct)
+
+  $ cat >> .hg/hgrc <<EOF
+  > [hooks]
+  > pretxncommit.unexpectedabort =
+  > EOF
+  $ hg status -u | while read f; do rm ${f}; done
+  $ hg revert --no-backup -q --all
+  $ hg qpush -q git
+  now at: git
+  $ hg qpush -q --move p3
+  now at: p3
+
+  $ hg status --rev "git^1" --rev . -arm
+  M a
+  A aa
+
   $ cd ..
 

tests/test-mq-qrefresh-replace-log-message.t

@@ -6,6 +6,8 b' Environment setup for MQ'
   $ hg qinit
 
 Should fail if no patches applied
+(this tests also that editor is not invoked if '--edit' is not
+specified)
 
   $ hg qrefresh
   no patches applied
@@ -16,7 +18,7 b' Should fail if no patches applied'
   $ hg qnew -m "First commit message" first-patch
   $ echo aaaa > file
   $ hg add file
-  $ hg qrefresh
+  $ HGEDITOR=cat hg qrefresh
 
 Should display 'First commit message'
 
@@ -126,10 +128,20 b' Test saving last-message.txt:'
   > EOF
 
   $ rm -f .hg/last-message.txt
+  $ hg status --rev "second-patch^1" -arm
+  A file2
   $ HGEDITOR="sh $TESTTMP/editor.sh" hg qrefresh -e
   ==== before editing
   Fifth commit message
    This is the 5th log message
+  
+  
+  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
+  HG: Leave message empty to use default message.
+  HG: --
+  HG: user: test
+  HG: branch 'default'
+  HG: added file2
   ====
   transaction abort!
   rollback completed
@@ -141,4 +153,6 b' Test saving last-message.txt:'
   Fifth commit message
    This is the 5th log message
   
+  
+  
   test saving last-message.txt