Scope HOMEBREW_NO_INSTALL_FROM_API to core formulae in brew audit

Library/Homebrew/brew.sh

@@ -790,7 +790,6 @@ then
   if [[ -z "${HOMEBREW_NO_INSTALL_FROM_API}" ]]
   then
     NO_INSTALL_FROM_API_COMMANDS=(
-      audit
       bottle
       bump-cask-pr
       bump-formula-pr

Library/Homebrew/dev-cmd/audit.rb

@@ -122,7 +122,8 @@ module Homebrew
     ENV.activate_extensions!
     ENV.setup_build_environment
 
-    audit_formulae, audit_casks = if args.tap
+    audit_formulae, audit_casks = without_api do # audit requires full Ruby source
+      if args.tap
         Tap.fetch(args.tap).then do |tap|
           [
             tap.formula_names.map { |name| Formula[name] },
@@ -148,6 +149,7 @@ module Homebrew
         args.named.to_formulae_and_casks
             .partition { |formula_or_cask| formula_or_cask.is_a?(Formula) }
       end
+    end
 
     if audit_formulae.empty? && audit_casks.empty?
       ofail "No matching formulae or casks to audit!"
@@ -209,8 +211,15 @@ module Homebrew
         display_cop_names:   args.display_cop_names?,
       }.compact
 
-      fa = FormulaAuditor.new(f, **options)
-      fa.audit
+      audit_proc = proc { FormulaAuditor.new(f, **options).tap(&:audit) }
+
+      # Audit requires full Ruby source so disable API.
+      # We shouldn't do this for taps however so that we don't unnecessarily require a full Homebrew/core clone.
+      fa = if f.core_formula?
+        without_api(&audit_proc)
+      else
+        audit_proc.call
+      end
 
       if fa.problems.any? || fa.new_formula_problems.any?
         formula_count += 1
@@ -316,4 +325,10 @@ module Homebrew
   def format_problem(message, location)
     "* #{location&.to_s&.dup&.concat(": ")}#{message.chomp.gsub("\n", "\n    ")}"
   end
+
+  def without_api(&block)
+    return yield unless Homebrew::EnvConfig.install_from_api?
+
+    with_env(HOMEBREW_NO_INSTALL_FROM_API: "1", HOMEBREW_AUTOMATICALLY_SET_NO_INSTALL_FROM_API: "1", &block)
+  end
 end