Better EMFILE fix.

Whenever an EMFILE occurs, rather than simply setting a 0 timeout,
progressively increase the timeout value each time, so as to ensure that
successive fs operations don't keep hitting the same wall.

lib/utils/graceful-fs.js

@@ -5,6 +5,8 @@
 // and other cleverness anywhere in the process without disrupting
 // anything else.
 var fs = require("fs")
+  , timeout = 0
+
 Object.keys(fs)
   .forEach(function (i) {
     exports[i] = (typeof fs[i] !== "function") ? fs[i]
@@ -14,7 +16,6 @@ Object.keys(fs)
                : graceful(fs[i])
   })
 
-
 function graceful (fn) { return function GRACEFUL () {
   var args = Array.prototype.slice.call(arguments)
     , cb_ = args.pop()
@@ -23,7 +24,7 @@ function graceful (fn) { return function GRACEFUL () {
     if (er && er.message.match(/^EMFILE, Too many open files/)) {
       return setTimeout(function () {
         GRACEFUL.apply(fs, args)
-      })
+      }, timeout ++)
     }
     cb_.apply(null, arguments)
   }