Depends does not match a previous alias

```
# trying to use a variable
---
input_name: data/sp500.html


tasks:
# create some data to analyze.
  -
    creates: data/sp500.html
    command:
      - mkdir -p $(dirname {{creates}})
      - wget http://en.wikipedia.org/wiki/List_of_S%26P_500_companies -O {{creates}}
    alias: get_data

  # extract the data
  -
    creates: data/sp500.csv
    depends: get_data
    command: python Code/parse_sp500.py data/sp500.html {{creates}}

```

Results in the error of get_data not being found