pack: fix infinite loop when packing w/ node_modules w/ dep cycles

Author: iarna

lib/utils/tar.js

@@ -147,8 +147,11 @@ BundledPacker.prototype.isBundled = function (name) {
   var pkg = this.tree.children.filter(nameMatch(name))[0]
   if (!pkg) return false
   var requiredBy = union([], pkg.package._requiredBy)
+  var seen = {}
   while (requiredBy.length) {
     var req = requiredBy.shift()
+    if (seen[req]) continue
+    seen[req] = true
     var reqPkg = this.flatTree[req]
     if (!reqPkg) continue
     if (reqPkg.parent === this.tree && bd.indexOf(reqPkg.package.name) !== -1) {