make it more obvious that temporary files are temporary files

When some operations are interrupted (or "die()'d" or crashed) then the
partial object/pack/index file may remain around.  Make it more obvious
in their name that those files are temporary stuff and can be cleaned up
if no operation is in progress.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/index-pack.c b/index-pack.c
index 61eb20e..6284fe3 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -139,7 +139,7 @@
 		if (!pack_name) {
 			static char tmpfile[PATH_MAX];
 			snprintf(tmpfile, sizeof(tmpfile),
-				 "%s/pack_XXXXXX", get_object_directory());
+				 "%s/tmp_pack_XXXXXX", get_object_directory());
 			output_fd = mkstemp(tmpfile);
 			pack_name = xstrdup(tmpfile);
 		} else
@@ -690,7 +690,7 @@
 	if (!index_name) {
 		static char tmpfile[PATH_MAX];
 		snprintf(tmpfile, sizeof(tmpfile),
-			 "%s/index_XXXXXX", get_object_directory());
+			 "%s/tmp_idx_XXXXXX", get_object_directory());
 		fd = mkstemp(tmpfile);
 		index_name = xstrdup(tmpfile);
 	} else {