commit: change "editform" to distinguish merge commits from other (--amend)

"editform" argument for "getcommiteditor" is decided according to the
format below:

  COMMAND[.ROUTE]

  - COMMAND: name of command
  - ROUTE: name of route, if there are two or more routes in COMMAND

This patch uses "amend.normal" and "amend.merge" as ROUTE of
"editform" instead of "amend", to distinguish merge commits from other
in "hg commit --amend" case.

mercurial/cmdutil.py

@@ -2133,7 +2133,7 b' def amend(ui, repo, commitfunc, old, ext'
 
                 user = opts.get('user') or old.user()
                 date = opts.get('date') or old.date()
-            editform = 'commit.amend'
+            editform = mergeeditform(old, 'commit.amend')
             editor = getcommiteditor(editform=editform, **opts)
             if not message:
                 editor = getcommiteditor(edit=True, editform=editform)

mercurial/help/config.txt

@@ -394,7 +394,8 b' customized message only for specific act'
 messages for each actions.
 
 - ``changeset.backout`` for :hg:`backout`
-- ``changeset.commit.amend`` for :hg:`commit --amend`
+- ``changeset.commit.amend.merge`` for :hg:`commit --amend` on merges
+- ``changeset.commit.amend.normal`` for :hg:`commit --amend` on other
 - ``changeset.commit.normal.merge`` for :hg:`commit` on merges
 - ``changeset.commit.normal.normal`` for :hg:`commit` on other
 - ``changeset.fetch`` for :hg:`fetch` (impling merge commit)

tests/test-commit-amend.t

@@ -145,7 +145,12 b' Disable default date on commit so when -'
 
 Test -u/-d:
 
-  $ hg ci --amend -u foo -d '1 0'
+  $ cat > .hg/checkeditform.sh <<EOF
+  > env | grep HGEDITFORM
+  > true
+  > EOF
+  $ HGEDITOR="sh .hg/checkeditform.sh" hg ci --amend -u foo -d '1 0'
+  HGEDITFORM=commit.amend.normal
   saved backup bundle to $TESTTMP/.hg/strip-backup/1cd866679df8-amend-backup.hg (glob)
   $ echo a >> a
   $ hg ci --amend -u foo -d '1 0'
@@ -619,7 +624,8 b' Amend a merge changeset (with renames an'
   zz renamed from z:69a1b67522704ec122181c0890bd16e9d3e7516a
   $ hg debugrename cc
   cc not renamed
-  $ hg ci --amend -m 'merge bar (amend message)'
+  $ HGEDITOR="sh .hg/checkeditform.sh" hg ci --amend -m 'merge bar (amend message)' --edit
+  HGEDITFORM=commit.amend.merge
   $ hg log --config diff.git=1 -pr .
   changeset:   24:832b50f2c271
   tag:         tip