t4301: verify that merge-tree fails on missing blob objects

We just fixed a problem where `merge-tree` would not fail on missing
tree objects. Let's ensure that that problem does not occur with blob
objects (and won't, in the future, either).

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

t/t4301-merge-tree-write-tree.sh

@@ -962,4 +962,20 @@ test_expect_success 'error out on missing tree objects' '
 	test_must_be_empty actual
 '
 
+test_expect_success 'error out on missing blob objects' '
+	echo 1 | git hash-object -w --stdin >blob1 &&
+	echo 2 | git hash-object -w --stdin >blob2 &&
+	echo 3 | git hash-object -w --stdin >blob3 &&
+	printf "100644 blob $(cat blob1)\tblob\n" | git mktree >tree1 &&
+	printf "100644 blob $(cat blob2)\tblob\n" | git mktree >tree2 &&
+	printf "100644 blob $(cat blob3)\tblob\n" | git mktree >tree3 &&
+	git init --bare missing-blob.git &&
+	cat blob1 blob3 tree1 tree2 tree3 |
+	git pack-objects missing-blob.git/objects/pack/side1-whatever-is-missing &&
+	test_must_fail git --git-dir=missing-blob.git >actual 2>err \
+		merge-tree --merge-base=$(cat tree1) $(cat tree2) $(cat tree3) &&
+	test_grep "unable to read blob object $(cat blob2)" err &&
+	test_must_be_empty actual
+'
+
 test_done