amend: enable support for using the secret phase

This comes from the evolve extension's version of amend.  The logic was already
in place, and appears to be the last of the trivial things that can be enabled.

Differential Revision: https://phab.mercurial-scm.org/D6856

hgext/amend.py

@@ -36,6 +36,7 b' command = registrar.command(cmdtable)'
      ('i', 'interactive', None, _('use interactive mode')),
      (b'', b'close-branch', None,
       _(b'mark a branch as closed, hiding it from the branch list')),
+     (b's', b'secret', None, _(b'use the secret phase for committing')),
      ('n', 'note', '', _('store a note on the amend')),
     ] + cmdutil.walkopts + cmdutil.commitopts + cmdutil.commitopts2
       + cmdutil.commitopts3,

relnotes/next

@@ -4,6 +4,8 b''
 
  * The amend extension supports the `--close-branch` argument.
 
+ * The amend extension supports the `--secret` argument.
+
  * The uncommit extension supports the `rewrite.update-timestamp` config option.
 
 == New Experimental Features ==

tests/test-amend.t

@@ -452,9 +452,10 b' Bad combination of date options:'
 
 Close branch
 
-  $ hg amend --close-branch
-  $ hg log --limit 1 -T 'close={get(extras, "close")}\n'
+  $ hg amend --secret --close-branch
+  $ hg log --limit 1 -T 'close={get(extras, "close")}\nphase={phase}\n'
   close=1
+  phase=secret
 
   $ cd ..