fix networking deadlock (#11)

* fix networking deadlock

* fix trailing spaces

Author: mafintosh

lib/sessions/network.js

@@ -43,15 +43,19 @@ module.exports = class NetworkSession {
     const core = this._corestore.get({ discoveryKey })
     const cbSet = new Set()
     const mainTimeouts = core.timeouts
+    let called = false
     core.timeouts = {
       get: (cb) => {
+        if (called) return cb(null)
         cbSet.add(() => mainTimeouts.get(cb))
       },
       update: (cb) => {
+        if (called) return cb(null)
         cbSet.add(() => mainTimeouts.update(cb))
       }
     }
     return () => {
+      called = true
       core.timeouts = mainTimeouts
       for (const cb of cbSet) cb()
     }