read-tree: fix eye-candy.

Anton Blanchard spotted that watching checkout stage of a clone
on a slow terminal takes ages because it forgot to clear the
"once a second happened" flag, so instead of updates the
percentage output for every file it checks out after the first
second has passed.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-read-tree.c

diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 085e11e..8d1a22d 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -376,6 +376,7 @@
 					fprintf(stderr, "%4u%% (%u/%u) done\r",
 						percent, cnt, total);
 					last_percent = percent;
+					progress_update = 0;
 				}
 			}
 		}