attr: Allow multiple changes to an attribute on the same line.

When using macros it isn't inconceivable to have an attribute
being set by a macro, and then being reset explicitly.

Signed-off-by: Henrik Grubbström <grubba@grubba.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

attr.c

@@ -599,7 +599,7 @@ static int fill_one(const char *what, struct match_attr *a, int rem)
 	struct git_attr_check *check = check_all_attr;
 	int i;
 
-	for (i = 0; 0 < rem && i < a->num_attr; i++) {
+	for (i = a->num_attr - 1; 0 < rem && 0 <= i; i--) {
 		struct git_attr *attr = a->state[i].attr;
 		const char **n = &(check[attr->attr_nr].value);
 		const char *v = a->state[i].setto;

t/t0003-attributes.sh

@@ -22,6 +22,8 @@ test_expect_success 'setup' '
 	(
 		echo "f	test=f"
 		echo "a/i test=a/i"
+		echo "onoff test -test"
+		echo "offon -test test"
 	) >.gitattributes &&
 	(
 		echo "g test=a/g" &&
@@ -44,6 +46,8 @@ test_expect_success 'attribute test' '
 	attr_check b/g unspecified &&
 	attr_check a/b/h a/b/h &&
 	attr_check a/b/d/g "a/b/d/*"
+	attr_check onoff unset
+	attr_check offon set
 
 '
 
@@ -58,6 +62,8 @@ a/b/g: test: a/b/g
 b/g: test: unspecified
 a/b/h: test: a/b/h
 a/b/d/g: test: a/b/d/*
+onoff: test: unset
+offon: test: set
 EOF
 
 	sed -e "s/:.*//" < expect | git check-attr --stdin test > actual &&