guix-package: Fix typo.

* guix-package.in (guix-package)[find-package]: Don't use `_' as the
  wildcard, to avoid collision with `gettext'.

guix-package.in

@@ -291,7 +291,7 @@ Report bugs to: ~a.~%") "@PACKAGE_BUGREPORT@"))
       (match (find-packages-by-name name version)
         ((p)
          (list name version sub-drv p))
-        ((p _ ...)
+        ((p p* ...)
          (format (current-error-port)
                  (_ "warning: ambiguous package specification `~a'~%")
                  request)