amend: add a --draft option to set phase to draft

Some users create commits in secret phase by default and then want to make them
draft so they can be uploaded. This patch adds a --draft option for that. We
already have a flag for changing the phase to secret, so it seems consistent to
have one for draft.

hgext/amend.py

@@ -46,6 +46,7 b' command = registrar.command(cmdtable)'
             _(b'mark a branch as closed, hiding it from the branch list'),
         ),
         (b's', b'secret', None, _(b'use the secret phase for committing')),
+        (b'', b'draft', None, _(b'use the draft phase for committing')),
         (b'n', b'note', b'', _(b'store a note on the amend')),
     ]
     + cmdutil.walkopts
@@ -64,6 +65,7 b' def amend(ui, repo, *pats, **opts):'
 
     See :hg:`help commit` for more details.
     """
+    cmdutil.check_at_most_one_arg(opts, 'draft', 'secret')
     cmdutil.check_note_size(opts)
 
     with repo.wlock(), repo.lock():

mercurial/cmdutil.py

@@ -3019,6 +3019,8 b' def amend(ui, repo, old, extra, pats, op'
         commitphase = None
         if opts.get(b'secret'):
             commitphase = phases.secret
+        elif opts.get(b'draft'):
+            commitphase = phases.draft
         newid = repo.commitctx(new)
         ms.reset()
 

tests/test-amend.t

@@ -560,6 +560,12 b' Close branch'
   close=1
   phase=secret
 
+`hg amend --draft` sets phase to draft
+
+  $ hg amend --draft -m declassified
+  $ hg log --limit 1 -T 'phase={phase}\n'
+  phase=draft
+
   $ cd ..
 
 Corner case of amend from issue6157: