build: loadInputs: remove redundant check for hasDigest

hasDigest would always be true when reaching this code, because the function
would return with an error when failing to resolve the digest;

    if !hasDigest {
        return nil, errors.Errorf("oci-layout reference %q could not be resolved", v.Path)
    }

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

build/opt.go

@@ -542,12 +542,7 @@ func loadInputs(ctx context.Context, d *driver.DriverHandle, inp Inputs, addVCSL
 			}
 			target.OCIStores[storeName] = store
 
-			layout := "oci-layout://" + storeName + ":" + tag
-			if hasDigest {
-				layout += "@" + dig
-			}
-
-			target.FrontendAttrs["context:"+k] = layout
+			target.FrontendAttrs["context:"+k] = "oci-layout://" + storeName + ":" + tag + "@" + dig
 			continue
 		}
 		st, err := os.Stat(v.Path)