etcd-tester:peer port parsing error

[fanminshi]

When Executing functional tester locally using goreman -f tools/functional-tester/Procfile start, some tests failed due to not to be able to parse the port from locally url correcly

09:52:38 stresser | panic: too many colons in address http://localhost:12380
09:52:38 stresser | goroutine 1 [running]:
09:52:38 stresser | panic(0x700460, 0xc420391220)
09:52:38 stresser |     /usr/local/go/src/runtime/panic.go
09:52:38 stresser | :500 +0x1a1
09:52:38 stresser | main.(*member).peerPort(0xc4201fa7e0, 0xc4204bd848)
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/member.go:173 +0x158
09:52:38 stresser | main.injectDropPort(0xc4201fa7e0, 0xc4204bdac0, 0x2)
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/failure_agent.go:81 +0x2b
09:52:38 stresser | main.(*failureOne).Inject(0xc420254a80, 0xc420140180, 0x0, 0xc4204bdac0, 0x2)
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/failure.go:64 +0x6c
09:52:38 stresser | main.(*tester).doRound(0xc420887680, 0x0, 0x1e, 0x8, 0x9)
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/tester.go:99 +0x2fd
09:52:38 stresser | main.(*tester).runLoop
09:52:38 stresser | (0xc420887680)
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/tester.go:49 +0x1ea
09:52:38 stresser | main.main()
09:52:38 stresser |     /Users/fanminshi/work/src/github.com/coreos/etcd/tools/functional-tester/etcd-tester/main.go:128 +0x10f7
09:52:38 stresser | Terminating stresser```