commit: create new amend changeset as secret correctly for "--secret" option Before this patch, "hg commit --amend --secret" doesn't create new amend changeset as secret, even though the internal function "commitfunc()" passed to "cmdutil.amend()" make "phases.new-commit" configuration as "secret" temporarily. "cmdutil.amend()" uses specified "commitfunc" only for temporary amend commit, and creates the final amend commit changeset by "localrepository.commitctx()" directly with memctx. This patch creates new amend changeset as secret correctly for "--secret" option, by changing "phases.new-commit" configuration temporarily before "localrepository.commitctx()".