data race

[dajohi]

==================
WARNING: DATA RACE
Write at 0x00c4352e40d0 by goroutine 71:
  main.(*rpcServer).jsonRPCRead()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6219 +0x957
  main.(*rpcServer).Start.func1()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6270 +0x211
  net/http.HandlerFunc.ServeHTTP()
      /usr/lib/go/src/net/http/server.go:1918 +0x51
  net/http.(*ServeMux).ServeHTTP()
      /usr/lib/go/src/net/http/server.go:2254 +0xa2
  net/http.serverHandler.ServeHTTP()
      /usr/lib/go/src/net/http/server.go:2619 +0xbc
  net/http.(*conn).serve()
      /usr/lib/go/src/net/http/server.go:1801 +0x83b

Previous write at 0x00c4352e40d0 by goroutine 174:
  main.(*rpcServer).jsonRPCRead.func1()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6061 +0xa7

Goroutine 71 (running) created at:
  net/http.(*Server).Serve()
      /usr/lib/go/src/net/http/server.go:2720 +0x37c
  main.(*rpcServer).Start.func3()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6300 +0x131

Goroutine 174 (finished) created at:
  main.(*rpcServer).jsonRPCRead()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6060 +0x7b4
  main.(*rpcServer).Start.func1()
      /home/j/go/src/github.com/decred/dcrd/rpcserver.go:6270 +0x211
  net/http.HandlerFunc.ServeHTTP()
      /usr/lib/go/src/net/http/server.go:1918 +0x51
  net/http.(*ServeMux).ServeHTTP()
      /usr/lib/go/src/net/http/server.go:2254 +0xa2
  net/http.serverHandler.ServeHTTP()
      /usr/lib/go/src/net/http/server.go:2619 +0xbc
  net/http.(*conn).serve()
      /usr/lib/go/src/net/http/server.go:1801 +0x83b
==================

[jrick]

This was encountered on commit 1329f87 (so the line numbers make sense)