test: add failing tests for "diff --stat" to t4049

There are a few problems in diff.c around --stat area, partially
caused by the recent 74faaa1 (Fix "git diff --stat" for interesting
- but empty - file changes, 2012-10-17), and largely caused by the
earlier change that introduced when --stat-count was added.

Add a few test pieces to t4049 to expose the issues.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4049-diff-stat-count.sh

@@ -4,12 +4,17 @@
 test_description='diff --stat-count'
 . ./test-lib.sh
 
-test_expect_success setup '
+test_expect_success 'setup' '
 	>a &&
 	>b &&
 	>c &&
 	>d &&
 	git add a b c d &&
+	git commit -m initial
+'
+
+test_expect_success 'limit output to 2 (simple)' '
+	git reset --hard &&
 	chmod +x c d &&
 	echo a >a &&
 	echo b >b &&
@@ -23,4 +28,43 @@ test_expect_success setup '
 	test_i18ncmp expect actual
 '
 
+test_expect_failure 'binary changes do not count in lines' '
+	git reset --hard &&
+	chmod +x c d &&
+	echo a >a &&
+	echo b >b &&
+	cat "$TEST_DIRECTORY"/test-binary-1.png >d &&
+	cat >expect <<-\EOF
+	 a | 1 +
+	 b | 1 +
+	 ...
+	 4 files changed, 2 insertions(+)
+	EOF
+	git diff --stat --stat-count=2 >actual &&
+	test_i18ncmp expect actual
+'
+
+test_expect_failure 'exclude unmerged entries from total file count' '
+	git reset --hard &&
+	echo a >a &&
+	echo b >b &&
+	git ls-files -s a >x &&
+	git rm -f d &&
+	for stage in 1 2 3
+	do
+		sed -e "s/ 0	a/ $stage	d/" x
+	done |
+	git update-index --index-info &&
+	echo d >d &&
+	chmod +x c d &&
+	cat >expect <<-\EOF
+	 a | 1 +
+	 b | 1 +
+	 ...
+	 4 files changed, 3 insertions(+)
+	EOF
+	git diff --stat --stat-count=2 >actual &&
+	test_i18ncmp expect actual
+'
+
 test_done