panic: ptrace status unexpected: got 31, wanted stopped

goroutine 5960311 [running]:
gvisor.googlesource.com/gvisor/pkg/sentry/platform/ptrace.(*thread).wait(0xc000bdee10, 0x0, 0xb3f6)
	pkg/sentry/platform/ptrace/subprocess.go:323 +0x38d
DIAGNOSIS:
I0407 16:32:13.830689   41535 x:0] ***************************
I0407 16:32:13.830742   41535 x:0] Args: [/syzkaller/managers/main/current/image -root /syzkaller/managers/main/workdir/gvisor_root -watchdog-action=panic -network=none -debug -platform=ptrace -file-access=shared -network=none debug -stacks ci-gvisor-main-0]
I0407 16:32:13.830756   41535 x:0] Version release-20190304.1-92-gee7e6d33b2a0
I0407 16:32:13.830761   41535 x:0] PID: 41535
I0407 16:32:13.830767   41535 x:0] UID: 0, GID: 0
I0407 16:32:13.830771   41535 x:0] Configuration:
I0407 16:32:13.830793   41535 x:0] 		RootDir: /syzkaller/managers/main/workdir/gvisor_root
I0407 16:32:13.830796   41535 x:0] 		Platform: ptrace
I0407 16:32:13.830841   41535 x:0] 		FileAccess: shared, overlay: false
I0407 16:32:13.830860   41535 x:0] 		Network: none, logging: false
I0407 16:32:13.830869   41535 x:0] 		Strace: false, max size: 1024, syscalls: []
I0407 16:32:13.830874   41535 x:0] ***************************
D0407 16:32:13.830897   41535 x:0] Load container "/syzkaller/managers/main/workdir/gvisor_root" "ci-gvisor-main-0"
D0407 16:32:13.832834   41535 x:0] Signal container "ci-gvisor-main-0": signal 0
D0407 16:32:13.832856   41535 x:0] Signal sandbox "ci-gvisor-main-0"
D0407 16:32:13.832862   41535 x:0] Connecting to sandbox "ci-gvisor-main-0"
D0407 16:32:13.833343   41535 x:0] urpc: successfully marshalled 96 bytes.
I0407 16:32:14.315959   41535 x:0] Found sandbox "ci-gvisor-main-0", PID: 42427
I0407 16:32:14.315990   41535 x:0] Retrieving sandbox stacks
D0407 16:32:14.315996   41535 x:0] Stacks sandbox "ci-gvisor-main-0"
D0407 16:32:14.316002   41535 x:0] Connecting to sandbox "ci-gvisor-main-0"
D0407 16:32:14.316117   41535 x:0] urpc: successfully marshalled 36 bytes.
W0407 16:32:14.372187   41535 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-main-0" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-main-0" stacks: urpc method "debug.Stacks" failed: connection reset by peer