gyp doesn't detect cycles between inputs and outputs of actions

[GoogleCodeExporter]

This file has the same file as input and output of an action. gyp should 
complain about this, but doesn't:

{ 'targets': [{
    'target_name': 'filtered_files',
    'type': 'none',
    'actions': [{
        'action_name': 'filter',
        'inputs': [
            'source/data/brkitr/ja.txt',
            'source/data/curr/am.txt',
        ],
        'outputs': [
            'tmp_icu_out/brkitr/ja.txt',
            'source/data/curr/am.txt',
        ],
        'action': [ 'python' ],
    }],
}]}

Original issue reported on code.google.com by thakis@chromium.org on 25 Mar 2015 at 6:11