Gemfile in groonga-client-model-0.9.1 vs Gemfile in groonga-client-model-0.9.2

@@ -18,6 +18,8 @@
 
 source "https://rubygems.org/"
 
 gemspec
 
-gem "groonga-client", path: "../groonga-client"
+if File.exist?("../groonga-client")
+  gem "groonga-client", path: "../groonga-client"
+end