Work around fish-shell/fish-shell#1168

Current version of Fish does not like pipelines in an else if statement. See fish-shell/fish-shell#1168 for more info.

Version info:
```
➜  fish --version
fish, version 2.1.0
➜  chruby --version
chruby: 0.3.8
chruby-fish: 0.5.4
```

/cc @tduffield @seth