Check for `bin` directory before cloning pyenv (#630)
Check for `bin` directory before cloning pyenv (#630)

Travis creates cached directories if they are not present, so the pyenv
repo was never getting cloned if the cache was empty.
google/oauth2client,google/oauth2client,clancychilds/oauth2client,clancychilds/oauth2client,googleapis/oauth2client,jonparrott/oauth2client,jonparrott/oauth2client,googleapis/oauth2client