GitDownloadStrategy: split up submodule update and checkout

Library/Homebrew/download_strategy.rb

@@ -350,13 +350,7 @@ class GitDownloadStrategy < AbstractDownloadStrategy
       end
       # http://stackoverflow.com/questions/160608/how-to-do-a-git-export-like-svn-export
       safe_system @@git, 'checkout-index', '-a', '-f', "--prefix=#{dst}/"
-      # check for submodules
+      checkout_submodules(dst) if submodules?
-      if File.exist?('.gitmodules')
-        safe_system @@git, 'submodule', 'init'
-        safe_system @@git, 'submodule', 'update'
-        sub_cmd = "#{@@git} checkout-index -a -f \"--prefix=#{dst}/$path/\""
-        safe_system @@git, 'submodule', '--quiet', 'foreach', '--recursive', sub_cmd
-      end
     end
   end
 
@@ -374,6 +368,10 @@ class GitDownloadStrategy < AbstractDownloadStrategy
     quiet_system @@git, "--git-dir", "#@clone/.git", "status", "-s"
   end
 
+  def submodules?
+    @clone.join(".gitmodules").exist?
+  end
+
   def clone_args
     args = %w{clone --no-checkout}
     args << '--depth' << '1' if support_depth?
@@ -405,6 +403,15 @@ class GitDownloadStrategy < AbstractDownloadStrategy
   def clone_repo
     safe_system @@git, *clone_args
   end
+
+  def update_submodules
+    safe_system @@git, 'submodule', 'update', '--init'
+  end
+
+  def checkout_submodules(dst)
+    sub_cmd = %W{#@@git checkout-index -a -f --prefix=#{dst}/$path/}
+    safe_system @@git, 'submodule', '--quiet', 'foreach', '--recursive', *sub_cmd
+  end
 end
 
 class CVSDownloadStrategy < AbstractDownloadStrategy