download_strategy: escape spaces in git submodule path.

for issue Homebrew/homebrew#36646

Closes Homebrew/homebrew#36649.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/download_strategy.rb

@@ -652,7 +652,7 @@ class GitDownloadStrategy < VCSDownloadStrategy
 
   def checkout_submodules(dst)
     escaped_clone_path = cached_location.to_s.gsub(/\//, '\/')
-    sub_cmd = "git checkout-index -a -f --prefix=#{dst}/${toplevel/#{escaped_clone_path}/}/$path/"
+    sub_cmd = "git checkout-index -a -f --prefix=#{dst}/${toplevel/#{escaped_clone_path}/}/\'$path\'/"
     quiet_safe_system "git", "submodule", "foreach", "--recursive", sub_cmd
   end
 end