Resurrect "git apply --flags -" to read from the standard input

The previous "parse-opt"ification broke git-apply reading from the
standard input.  "git apply A - C <B" is supposed to read patches from
files A, B and C in this order.

Before "parse-opt"ification, we used be able to:

	git apply --stat - --apply <A B

to read the patch from file A, showing only the diffstat, and then read the
patch from file B, showing the diffstat and actually applying it.  Even
with this fix we cannot do that anymore, but that is so crazy use case I
do not think anybody sane relied on such a broken behaviour.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-apply.c

@@ -3140,16 +3140,6 @@ static int git_apply_config(const char *var, const char *value, void *cb)
 	return git_default_config(var, value, cb);
 }
 
-static int option_parse_stdin(const struct option *opt,
-			      const char *arg, int unset)
-{
-	int *errs = opt->value;
-
-	*errs |= apply_patch(0, "<stdin>", options);
-	read_stdin = 0;
-	return 0;
-}
-
 static int option_parse_exclude(const struct option *opt,
 				const char *arg, int unset)
 {
@@ -3218,9 +3208,6 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 	const char *whitespace_option = NULL;
 
 	struct option builtin_apply_options[] = {
-		{ OPTION_CALLBACK, '-', NULL, &errs, NULL,
-			"read the patch from the standard input",
-			PARSE_OPT_NOARG, option_parse_stdin },
 		{ OPTION_CALLBACK, 0, "exclude", NULL, "path",
 			"don´t apply changes matching the given path",
 			0, option_parse_exclude },
@@ -3302,7 +3289,11 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 		const char *arg = argv[i];
 		int fd;
 
-		if (0 < prefix_length)
+		if (!strcmp(arg, "-")) {
+			errs |= apply_patch(0, "<stdin>", options);
+			read_stdin = 0;
+			continue;
+		} else if (0 < prefix_length)
 			arg = prefix_filename(prefix, prefix_length, arg);
 
 		fd = open(arg, O_RDONLY);

t/t4106-apply-stdin.sh

+#!/bin/sh
+
+test_description='git apply --numstat - <patch'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo hello >text &&
+	git add text &&
+	echo goodbye >text &&
+	git diff >patch
+'
+
+test_expect_success 'git apply --numstat - < patch' '
+	echo "1	1	text" >expect &&
+	git apply --numstat - <patch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'git apply --numstat - < patch patch' '
+	for i in 1 2; do echo "1	1	text"; done >expect &&
+	git apply --numstat - < patch patch >actual &&
+	test_cmp expect actual
+'
+
+test_done