Save only when new images were created

Ignore restored images when checking for new images. Restored
images are still always added to the new cache. This is so that
unchanged images aren't lost when other images are rebuilt.

post.ts

@@ -21,17 +21,15 @@ const main = async () => {
   assertType<string[]>(restoredImages)
 
   const imageDetector = new ImageDetector()
-  if (await imageDetector.checkIfImageHasAdded(restoredImages)) {
-    core.info(`Key ${restoredKey} already exists, not saving cache.`)
-    return
-  }
 
-  const imagesToSave = await imageDetector.getImagesShouldSave(alreadyExistingImages)
-  if (imagesToSave.length < 1) {
+  const existingAndRestoredImages = alreadyExistingImages.concat(restoredImages)
+  const newImages = await imageDetector.getImagesShouldSave(existingAndRestoredImages)
+  if (newImages.length < 1) {
     core.info(`There is no image to save.`)
     return
   }
 
+  const imagesToSave = await imageDetector.getImagesShouldSave(alreadyExistingImages)
   const layerCache = new LayerCache(imagesToSave)
   layerCache.concurrency = parseInt(core.getInput(`concurrency`, { required: true }), 10)
 

src/ImageDetector.ts

@@ -17,9 +17,4 @@ export class ImageDetector {
     alreadRegisteredImages.forEach(image => resultSet.delete(image))
     return Array.from(resultSet)
   }
-
-  async checkIfImageHasAdded(restoredImages: string[]): Promise<boolean> {
-    const existing = await this.getExistingImages()
-    return JSON.stringify(restoredImages) === JSON.stringify(existing)
-  }
 }