builtin-clone: fix initial checkout

Somewhere in the process of finishing up builtin-clone, the update of
the working tree was lost.  This was due to not using the option "merge"
for unpack_trees().

Breakage noticed by Kevin Ballard.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Tested-by: Jeff King <peff@peff.net>
Acked-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-clone.c

@@ -525,7 +525,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 		memset(&opts, 0, sizeof opts);
 		opts.update = 1;
+		opts.merge = 1;
+		opts.fn = oneway_merge;
 		opts.verbose_update = !option_quiet;
+		opts.src_index = &the_index;
 		opts.dst_index = &the_index;
 
 		tree = parse_tree_indirect(remote_head->old_sha1);

t/t5601-clone.sh

@@ -23,4 +23,11 @@ test_expect_success 'clone with excess parameters' '
 
 '
 
+test_expect_success 'clone checks out files' '
+
+	git clone src dst &&
+	test -f dst/file
+
+'
+
 test_done