Running YAML E2E tests causes invalid memory address error in the controller

[mgencur]

Expected Behavior

All yaml e2e tests passing.

Actual Behavior

Initially, the individual yaml files are being processed successfully and builds complete but after some random time the controller throws this error.
`{"level":"info","logger":"controller.controller","caller":"controller/controller.go:232","msg":"Successfully synced "build-tests/git-tag"","knative.dev/controller":"controller","knative.dev/controller":"controller"}
E1107 13:59:36.966275 1 runtime.go:66] Observed a panic: "invalid memory address or nil pointer dereference" (runtime error: invalid memory address or nil pointer dereference)
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:72
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:65
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:51
/usr/local/go/src/runtime/asm_amd64.s:573
/usr/local/go/src/runtime/panic.go:502q
/usr/local/go/src/runtime/panic.go:63
/usr/local/go/src/runtime/signal_unix.go:388
/go/src/github.com/knative/build/pkg/reconciler/build/build.go:161
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:225
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:234
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:159
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:133
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:134
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:88
/usr/local/go/src/runtime/asm_amd64.s:2361
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xedf5ee]

goroutine 115 [running]:
github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/runtime.HandleCrash(0x0, 0x0, 0x0)
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:58 +0x107
panic(0xfff700, 0x1938a60)
/usr/local/go/src/runtime/panic.go:502 +0x229
github.com/knative/build/pkg/reconciler/build.(*Reconciler).Reconcile(0xc4200e93b0, 0x1253ce0, 0xc420661500, 0xc4206bb640, 0x1b, 0x3bc2d3200, 0x1949be0)
/go/src/github.com/knative/build/pkg/reconciler/build/build.go:161 +0x31e
github.com/knative/build/vendor/github.com/knative/pkg/controller.(*Impl).processNextWorkItem.func1(0xc4203baf40, 0xfa0f40, 0xc4206d96a0, 0x0, 0x0)
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:225 +0x328
github.com/knative/build/vendor/github.com/knative/pkg/controller.(*Impl).processNextWorkItem(0xc4203baf40, 0x1)
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:234 +0x6a
github.com/knative/build/vendor/github.com/knative/pkg/controller.(*Impl).Run.func1()
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:159 +0x36
github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait.JitterUntil.func1(0xc4203c1f80)
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:133 +0x54
github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait.JitterUntil(0xc4203c1f80, 0x3b9aca00, 0x0, 0xc420990001, 0xc42003e060)
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:134 +0xbd
github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait.Until(0xc4203c1f80, 0x3b9aca00, 0xc42003e060)
/go/src/github.com/knative/build/vendor/k8s.io/apimachinery/pkg/util/wait/wait.go:88 +0x4d
created by github.com/knative/build/vendor/github.com/knative/pkg/controller.(*Impl).Run
/go/src/github.com/knative/build/vendor/github.com/knative/pkg/controller/controller.go:158 +0x115
`

Steps to Reproduce the Problem

1. Run yaml e2e tests

Additional Info

I've run these tests on OpenShift (OKD 3.11) but I'm not sure it's related.

[shashwathi]

@mgencur : What version of build are you running?

[mgencur]

@shashwathi tried HEAD of master branch a few day ago (HEAD=3e2db7c)