E121: Undefined variable: name

bug fix
```
E121: Undefined variable: name
E116: Invalid arguments for function split(name, '/')[-1]
E15: Invalid expression: (a:protocol ==# 'ssh') ? 'git@gist.github.com:' . split(name, '/')[-1] : a:protocol . '://gist.github.com/'. split(name, '/')[-1]
Failed parse name "git://gist.github.com/9133200.git" and args {'recipe': '', 'default': '_', 'script_type': 'plugin'}
```
Merge pull request #333 from soramugi/undef_name

E121: Undefined variable: name