Returns a directory if it is in path and executable bit is set

[ptierno]

I ran into an issue where i had a directory in my path which contained a subdirectory. While using which to find an actual executable, it returned the path to the directory instead since it was first in the path:

➜  which ls -l
total 0
drwxr-xr-x  2 ptierno  staff  68 Aug 25 19:02 directory
➜  which export PATH=`pwd`:$PATH
➜  which node
> var which = require('which');
undefined
>
> which.sync('directory')
'/Users/ptierno/which/directory'                                                                                                                                                    

If I remove the executable bit from the directory then the directory doesnt get returned (which is what I would expect).

➜  which chmod -x directory
➜  which node
> var which = require('which');
undefined
> which.sync('directory')
Error: not found: directory
    at getNotFoundError (/Users/ptierno/node_modules/which/which.js:14:12)
    at Function.whichSync [as sync] (/Users/ptierno/node_modules/which/which.js:132:9)
    at repl:1:7
    at REPLServer.defaultEval (repl.js:272:27)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:441:10)
    at emitOne (events.js:101:20)
    at REPLServer.emit (events.js:188:7)
    at REPLServer.Interface._onLine (readline.js:224:10)
>

Might be a good idea to do a check to ensure the value being returned is an actual executable file and not a directory.

[isaacs]

Updating isexe made which's tests break on Windows, so this isn't quite finished or ready to ship yet. I'll try to investigate this soon.

[isaacs]

Fixed. Not sure how or if the tests ever passed on Windows, without d24dc05.