rbinstall.rb: fix the position to expand files

As `spec.files` is used for `executables` and so on, the expanded
list needs to be located at the same place.

tool/rbinstall.rb

@@ -874,24 +874,24 @@ end
 def load_gemspec(file, expanded = false)
   file = File.realpath(file)
   code = File.read(file, encoding: "utf-8:-")
-  code.gsub!(/`git.*?`/m, '""')
+  code.gsub!(/(?:`git[^\`]*`|%x\[git[^\]]*\])\.split\(\"(?:\\.|[^\"])*\"\)/m) do
-  code.gsub!(/%x\[git.*?\]/m, '""')
+    files = []
-  spec = eval(code, binding, file)
-  unless Gem::Specification === spec
-    raise TypeError, "[#{file}] isn't a Gem::Specification (#{spec.class} instead)."
-  end
-  spec.loaded_from = file
-
-  # gather expanded bundled gem files
     if expanded
       base = File.dirname(file)
       Dir.glob("**/*", File::FNM_DOTMATCH, base: base) do |n|
         next if n.start_with?(".git") # git related files are useless
         case File.basename(n); when ".", ".."; next; end
         next if File.directory?(File.join(base, n))
-      spec.files << n
+        files << n.dump
       end
     end
+    "[" + files.join(", ") + "]"
+  end
+  spec = eval(code, binding, file)
+  unless Gem::Specification === spec
+    raise TypeError, "[#{file}] isn't a Gem::Specification (#{spec.class} instead)."
+  end
+  spec.loaded_from = file
 
   spec
 end