Fix source key handling for interim tiles

src/ol/source/DataTile.js

@@ -111,6 +111,7 @@ class DataTileSource extends TileSource {
     }
 
     const tile = new DataTile({tileCoord: [z, x, y], loader: loader});
+    tile.key = this.getKey();
     tile.addEventListener(EventType.CHANGE, this.handleTileChange_);
 
     this.tileCache.set(tileCoordKey, tile);

src/ol/source/GeoTIFF.js

@@ -197,6 +197,8 @@ class GeoTIFFSource extends DataTile {
      */
     this.error_ = null;
 
+    this.setKey(this.sourceInfo_.map((source) => source.url).join(','));
+
     const self = this;
     const requests = new Array(numSources);
     for (let i = 0; i < numSources; ++i) {