update pipeline results in transport closing and pachd crash

[suneeta-mall]

What happened?:
run pachctl update-pipeline -f <>.json intermittently results sends message of transport closing .. crashing the pachd pod.

We have seen this happening 4 times since yesterday. Pachd log is

2018-08-06T06:13:06Z INFO pps.API.call64 {"duration":0.003014112,"request":{"output_commit":{"repo":{"name":"PX"},"id":"2f91fd5dca3841d096657a2b94190b91"},"block_state":true},"response":null} []
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x16aae37]

goroutine 17973 [running]:
github.com/pachyderm/pachyderm/src/server/pps/server.(*apiServer).InspectJob(0xc4209e7180, 0x7fd1dfa38208, 0xc420890540, 0xc4209b7b20, 0x0, 0x0, 0x0)
    /go/src/github.com/pachyderm/pachyderm/src/server/pps/server/api_server.go:506 +0x317
github.com/pachyderm/pachyderm/src/server/vendor/github.com/pachyderm/pachyderm/src/client/pps._API_InspectJob_Handler(0x1b94420, 0xc4209e7180, 0x7fd1dfa38208, 0xc420890540, 0xc42047d030, 0x0, 0x0, 0x0, 0xc420dd8ad8, 0xcb08a4)
    /go/src/github.com/pachyderm/pachyderm/src/server/vendor/github.com/pachyderm/pachyderm/src/client/pps/pps.pb.go:3185 +0x241
github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc.(*Server).processUnaryRPC(0xc4200f8840, 0x1dabe80, 0xc420405b00, 0xc4206ac000, 0xc4204ec360, 0x2a417d8, 0x0, 0x0, 0x0)
    /go/src/github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc/server.go:920 +0x848
github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc.(*Server).handleStream(0xc4200f8840, 0x1dabe80, 0xc420405b00, 0xc4206ac000, 0x0)
    /go/src/github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc/server.go:1142 +0x1318
github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc.(*Server).serveStreams.func1.1(0xc4203c6fa0, 0xc4200f8840, 0x1dabe80, 0xc420405b00, 0xc4206ac000)
    /go/src/github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc/server.go:637 +0x9f
created by github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc.(*Server).serveStreams.func1
    /go/src/github.com/pachyderm/pachyderm/src/server/vendor/google.golang.org/grpc/server.go:635 +0xa1

What you expected to happen?:
update to succeed

How to reproduce it (as minimally and precisely as possible)?:
execute update pipeline

Anything else we need to know?:

Environment?:

• Kubernetes version (use kubectl version):
• Pachyderm CLI version (use pachctl version):
• Cloud provider (e.g. aws, azure, gke) or local deployment (e.g. minikube vs dockerized k8s):
• OS (e.g. from /etc/os-release):
• Others: