Merge 'pk/rebase-in-c'

This is the first batch of the patches that turn `git rebase` into
a builtin.

This not only helps performance on Windows, but *especially* makes
things more robust, as no MSYS2 Bash will be required to run this
command any longer.

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

git.c

@@ -522,6 +522,12 @@ static struct cmd_struct commands[] = {
 	{ "push", cmd_push, RUN_SETUP },
 	{ "range-diff", cmd_range_diff, RUN_SETUP | USE_PAGER },
 	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
+	/*
+	 * NEEDSWORK: Until the rebase is independent and needs no redirection
+	 * to rebase shell script this is kept as is, then should be changed to
+	 * RUN_SETUP | NEED_WORK_TREE
+	 */
+	{ "rebase", cmd_rebase },
 	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },