Multipolygon without inner do not assign tags

[joaokho]

If Big polygon that contain multiple ways , and inside is not any inner element, return type Multipolygon/Relation but do not apply any tags on multipolygon. tags only on ways. When display it's not correct, Example big river polygon that contains multiple ways but do not has inner element did not display correctly

[joaokho]

Because on function SplitLongWays calling function mergeIntoNewRelation did not sent features tag when created new Relation. it's only paramater way_parts that only set of class Ways that did not contains any tags