Attempt to reduce memory churn when processing package metadata

tests/model-package-metadata.scm

@@ -48,6 +48,9 @@
          (inferior-packages->license-id-lists
           conn
           '#((("License 1"
+               "https://gnu.org/licenses/test-1.html"
+               "https://example.com/why-license-1"))
+             (("License 1"
                "https://gnu.org/licenses/test-1.html"
                "https://example.com/why-license-1"))))))
 
@@ -74,7 +77,8 @@
                 conn
                 mock-package-metadata
                 (test-license-set-ids conn))
-             (#(x) (number? x))))
+             (#(x y) (and (number? x)
+                          (number? y)))))
          #:always-rollback? #t))
 
       (with-postgresql-transaction