Revert "disable license check for new formulae"

Library/Homebrew/dev-cmd/audit.rb

@@ -333,8 +333,7 @@ module Homebrew
     ].freeze
 
     def audit_license
-      return if formula.license.blank?
-
+      if formula.license.present?
         if @spdx_data["licenses"].any? { |lic| lic["licenseId"] == formula.license }
           return unless @online
 
@@ -349,6 +348,9 @@ module Homebrew
         else
           problem "#{formula.license} is not a standard SPDX license."
         end
+      elsif @new_formula
+        problem "No license specified for package."
+      end
     end
 
     def audit_deps

Library/Homebrew/test/dev-cmd/audit_spec.rb

@@ -99,6 +99,18 @@ module Homebrew
         expect(fa.problems).to be_empty
       end
 
+      it "detects no license info" do
+        fa = formula_auditor "foo", <<~RUBY, spdx_data: spdx_data, new_formula: true
+          class Foo < Formula
+            url "https://brew.sh/foo-1.0.tgz"
+            license ""
+          end
+        RUBY
+
+        fa.audit_license
+        expect(fa.problems.first).to match "No license specified for package."
+      end
+
       it "detects if license is not a standard spdx-id" do
         fa = formula_auditor "foo", <<~RUBY, spdx_data: spdx_data, new_formula: true
           class Foo < Formula