sequencer (rebase -i): implement the 'reword' command

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

sequencer.c

@@ -663,6 +663,7 @@ enum todo_command {
 	TODO_PICK,
 	TODO_REVERT,
 	TODO_EDIT,
+	TODO_REWORD,
 	TODO_FIXUP,
 	TODO_SQUASH,
 	TODO_EXEC,
@@ -676,6 +677,7 @@ static struct {
 	{ 'p', "pick" },
 	{ 0,   "revert" },
 	{ 'e', "edit" },
+	{ 'r', "reword" },
 	{ 'f', "fixup" },
 	{ 's', "squash" },
 	{ 'x', "exec" },
@@ -853,7 +855,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 	else
 		parent = commit->parents->item;
 
-	if (opts->allow_ff && !is_fixup(command) &&
+	if (opts->allow_ff && !is_fixup(command) && command != TODO_REWORD &&
 	    ((parent && !hashcmp(parent->object.oid.hash, head)) ||
 	     (!parent && unborn)))
 		fast_forward = 1;
@@ -922,7 +924,9 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 		}
 	}
 
-	if (is_fixup(command)) {
+	if (command == TODO_REWORD)
+		edit = 1;
+	else if (is_fixup(command)) {
 		/* TODO: reflog action */
 		if (update_squash_messages(command, commit, opts))
 			return -1;