delete when empty at `AssembleEntryWithAcp`

`PutBucketAcl/PutObjectAcl` allow request with empty grants, `AssembleEntryWithAcp`  shouldn't skip empty value

Signed-off-by: changlin.shi <changlin.shi@ly.com>

weed/s3api/s3acl/acl_helper.go

@@ -411,6 +411,8 @@ func AssembleEntryWithAcp(objectEntry *filer_pb.Entry, objectOwner string, grant
 
 	if len(objectOwner) > 0 {
 		objectEntry.Extended[s3_constants.ExtAmzOwnerKey] = []byte(objectOwner)
+	} else {
+		delete(objectEntry.Extended, s3_constants.ExtAmzOwnerKey)
 	}
 
 	if len(grants) > 0 {
@@ -420,6 +422,8 @@ func AssembleEntryWithAcp(objectEntry *filer_pb.Entry, objectOwner string, grant
 			return s3err.ErrInvalidRequest
 		}
 		objectEntry.Extended[s3_constants.ExtAmzAclKey] = grantsBytes
+	} else {
+		delete(objectEntry.Extended, s3_constants.ExtAmzAclKey)
 	}
 
 	return s3err.ErrNone

weed/s3api/s3acl/acl_helper_test.go

@@ -487,8 +487,9 @@ func TestDetermineReqGrants(t *testing.T) {
 
 func TestAssembleEntryWithAcp(t *testing.T) {
 	defaultOwner := "admin"
-	{
+
 	//case1
+	//assemble with non-empty grants
 	expectOwner := "accountS"
 	expectGrants := []*s3.Grant{
 		{
@@ -512,22 +513,19 @@ func TestAssembleEntryWithAcp(t *testing.T) {
 	if !grantsEquals(resultGrants, expectGrants) {
 		t.Fatal("grants not expect")
 	}
-	}
-	{
+
 	//case2
-		entry := &filer_pb.Entry{}
+	//assemble with empty grants (override)
 	AssembleEntryWithAcp(entry, "", nil)
-
-		resultOwner := GetAcpOwner(entry.Extended, defaultOwner)
+	resultOwner = GetAcpOwner(entry.Extended, defaultOwner)
 	if resultOwner != defaultOwner {
 		t.Fatalf("owner not expect")
 	}
 
-		resultGrants := GetAcpGrants(entry.Extended)
+	resultGrants = GetAcpGrants(entry.Extended)
 	if len(resultGrants) != 0 {
 		t.Fatal("grants not expect")
 	}
-	}
 
 }