sequencer: mark action_name() for translation

The definition of this function goes back all the way to 043a449
(sequencer: factor code out of revert builtin, 2012-01-11), long before a
serious effort was made to translate all the error messages.

It is slightly out of the context of the current patch series (whose
purpose it is to re-implement the performance critical parts of the
interactive rebase in C) to make the error messages in the sequencer
translatable, but what the heck. We'll just do it while we're looking at
this part of the code.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -168,7 +168,7 @@ int sequencer_remove_state(struct replay_opts *opts)
 
 static const char *action_name(const struct replay_opts *opts)
 {
-	return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
+	return opts->action == REPLAY_REVERT ? N_("revert") : N_("cherry-pick");
 }
 
 struct commit_message {
@@ -300,10 +300,10 @@ static struct tree *empty_tree(void)
 static int error_dirty_index(struct replay_opts *opts)
 {
 	if (read_cache_unmerged())
-		return error_resolve_conflict(action_name(opts));
+		return error_resolve_conflict(_(action_name(opts)));
 
 	error(_("Your local changes would be overwritten by %s."),
-		action_name(opts));
+		_(action_name(opts)));
 
 	if (advice_commit_before_merge)
 		advise(_("Commit your changes or stash them to proceed."));
@@ -321,7 +321,7 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from,
 	if (checkout_fast_forward(from, to, 1))
 		return -1; /* the callee should have complained already */
 
-	strbuf_addf(&sb, _("%s: fast-forward"), action_name(opts));
+	strbuf_addf(&sb, _("%s: fast-forward"), _(action_name(opts)));
 
 	transaction = ref_transaction_begin(&err);
 	if (!transaction ||
@@ -397,7 +397,7 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 	    write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
 		/* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 		return error(_("%s: Unable to write new index file"),
-			action_name(opts));
+			_(action_name(opts)));
 	rollback_lock_file(&index_lock);
 
 	if (opts->signoff)
@@ -835,14 +835,14 @@ static int read_and_refresh_cache(struct replay_opts *opts)
 	if (read_index_preload(&the_index, NULL) < 0) {
 		rollback_lock_file(&index_lock);
 		return error(_("git %s: failed to read the index"),
-			action_name(opts));
+			_(action_name(opts)));
 	}
 	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 	if (the_index.cache_changed && index_fd >= 0) {
 		if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK)) {
 			rollback_lock_file(&index_lock);
 			return error(_("git %s: failed to refresh the index"),
-				action_name(opts));
+				_(action_name(opts)));
 		}
 	}
 	rollback_lock_file(&index_lock);