spdy sends too many closes, listen to only one

Author: daviddias

src/index.js

@@ -108,7 +108,7 @@ function Swarm (peerInfo) {
     if (this.muxedConns[key]) {
       const muxer = this.muxedConns[key].muxer
       muxer.end()
-      muxer.on('close', () => {
+      muxer.once('close', () => {
         delete this.muxedConns[key]
         callback()
       })

test/09-swarm-with-muxing.node.js

@@ -218,7 +218,7 @@ describe('high level API - with everything mixed all together!', function () {
     const ready = () => ++count === 3 ? done() : null
 
     swarmB.once('peer-mux-closed', (peerInfo) => {
-      expect(Object.keys(swarmA.muxedConns).length).to.equal(0)
+      expect(Object.keys(swarmB.muxedConns).length).to.equal(0)
       ready()
     })