Generate full-size SHA256 IDs for images and containers

Upstream-commit: 190e2fa50f62c0b2a497dac39a5154bd35e46b3a
Component: engine

components/engine/image.go

@@ -175,7 +175,7 @@ func ComputeId(content io.Reader) (string, error) {
 	if _, err := io.Copy(h, content); err != nil {
 		return "", err
 	}
-	return fmt.Sprintf("%x", h.Sum(nil)[:8]), nil
+	return fmt.Sprintf("%x", h.Sum(nil)), nil
 }
 
 // Image includes convenience proxy functions to its graph