t1000: fix case table.

Case #10 is not handled with unpack-trees.c:threeway_merge()
internally, unless under the agressive rule, and it is not a
bug.  As the test expects, ND (one side did not do anything,
other side deleted) case was meant to be handled by the caller's
policy (e.g. git-merge-one-file or git-merge-recursive).

Signed-off-by: Junio C Hamano <junkio@cox.net>

t/t1000-read-tree-m-3way.sh

@@ -184,7 +184,7 @@ checked.
   9  exists  O!=A    missing   no merge    must match A and be
                                            up-to-date, if exists.
  ------------------------------------------------------------------
- 10  exists  O==A    missing   remove      ditto
+ 10  exists  O==A    missing   no merge    must match A
  ------------------------------------------------------------------
  11  exists  O!=A    O!=B      no merge    must match A and be
                      A!=B                  up-to-date, if exists.

unpack-trees.c

@@ -786,7 +786,7 @@ int threeway_merge(struct cache_entry **stages,
 
 	o->nontrivial_merge = 1;
 
-	/* #2, #3, #4, #6, #7, #9, #11. */
+	/* #2, #3, #4, #6, #7, #9, #10, #11. */
 	count = 0;
 	if (!head_match || !remote_match) {
 		for (i = 1; i < o->head_idx; i++) {