Merge pull request #16 from romainl/master

Trying something to fix the mingw issue.

Author: kimmobrunfeldt

utils.js

@@ -7,7 +7,7 @@ var shellQuote = require('shell-quote');
 // We assume that Windows provides COMSPEC env variable
 // and other platforms provide SHELL env variable
 var SHELL_PATH = process.env.SHELL || process.env.COMSPEC;
-var EXECUTE_OPTION = process.env.COMSPEC !== undefined ? '/c' : '-c';
+var EXECUTE_OPTION = process.env.COMSPEC !== undefined && process.env.SHELL === undefined ? '/c' : '-c';
 
 // XXX: Wrapping tos to a promise is a bit wrong abstraction. Maybe RX suits
 // better?