Merge branch 'jc/apply-reject-noop-hunk'

"git apply" cannot diagnose a patch corruption when the breakage is
to mark the length of the hunk shorter than it really is on the
hunk header line "@@ -l,k +m,n @@"; one special case it could is
when the hunk becomes no-op (e.g. k == n == 2 for two-line context
patch output), and it learned how to do so.

* jc/apply-reject-noop-hunk:
  apply: reject a hunk that does not do anything

builtin/apply.c

@@ -1638,6 +1638,9 @@ static int parse_fragment(const char *line, unsigned long size,
 	}
 	if (oldlines || newlines)
 		return -1;
+	if (!deleted && !added)
+		return -1;
+
 	fragment->leading = leading;
 	fragment->trailing = trailing;
 

t/t4136-apply-check.sh

@@ -16,4 +16,17 @@ test_expect_success 'apply --check exits non-zero with unrecognized input' '
 	EOF
 '
 
+test_expect_success 'apply exits non-zero with no-op patch' '
+	cat >input <<-\EOF &&
+	diff --get a/1 b/1
+	index 6696ea4..606eddd 100644
+	--- a/1
+	+++ b/1
+	@@ -1,1 +1,1 @@
+	 1
+	EOF
+	test_must_fail git apply --stat input &&
+	test_must_fail git apply --check input
+'
+
 test_done