Cache pkgutil results at the source

Library/Homebrew/macos.rb

@@ -234,7 +234,9 @@ module MacOS extend self
   end
 
   def pkgutil_info id
-    `/usr/sbin/pkgutil --pkg-info "#{id}" 2>/dev/null`.strip
+    (@pkginfo ||= {}).fetch(id.to_s) do
+      @pkginfo[id.to_s] = `/usr/sbin/pkgutil --pkg-info "#{id}" 2>/dev/null`.strip
+    end
   end
 end
 

Library/Homebrew/os/mac/xcode.rb

@@ -182,16 +182,17 @@ module MacOS::CLT extend self
     !latest_version?
   end
 
-  def version
-    # The pkgutils calls are slow, don't repeat if no CLT installed.
-    return @version if @version_determined
-
-    @version_determined = true
   # Version string (a pretty damn long one) of the CLT package.
   # Note, that different ways to install the CLTs lead to different
   # version numbers.
-    @version ||= [STANDALONE_PKG_ID, FROM_XCODE_PKG_ID].find do |id|
-      MacOS.pkgutil_info(id) =~ /version: (.+)$/
-    end && $1
+  def version
+    @version ||= detect_version
+  end
+
+  def detect_version
+    [STANDALONE_PKG_ID, FROM_XCODE_PKG_ID].find do |id|
+      version = MacOS.pkgutil_info(id)[/version: (.+)$/, 1]
+      return version if version
+    end
   end
 end