panic: ptrace status unexpected: got 31, wanted stopped

goroutine 3266339 [running]:
gvisor.googlesource.com/gvisor/pkg/sentry/platform/ptrace.(*thread).wait(0xc00108a5a0, 0x0, 0xd76a)
DIAGNOSIS:
I0410 17:27:45.066481   41858 x:0] ***************************
I0410 17:27:45.066564   41858 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-2]
I0410 17:27:45.066596   41858 x:0] Version release-20190304.1-104-g0e14e48b84fd
I0410 17:27:45.066642   41858 x:0] PID: 41858
I0410 17:27:45.066650   41858 x:0] UID: 0, GID: 0
I0410 17:27:45.066654   41858 x:0] Configuration:
I0410 17:27:45.066657   41858 x:0] 		RootDir: /syzkaller/managers/main/workdir/gvisor_root
I0410 17:27:45.066661   41858 x:0] 		Platform: ptrace
I0410 17:27:45.066671   41858 x:0] 		FileAccess: shared, overlay: false
I0410 17:27:45.066694   41858 x:0] 		Network: none, logging: false
I0410 17:27:45.066700   41858 x:0] 		Strace: false, max size: 1024, syscalls: []
I0410 17:27:45.066705   41858 x:0] ***************************
D0410 17:27:45.067012   41858 x:0] Load container "/syzkaller/managers/main/workdir/gvisor_root" "ci-gvisor-main-2"
D0410 17:27:45.078633   41858 x:0] Signal container "ci-gvisor-main-2": signal 0
D0410 17:27:45.078660   41858 x:0] Signal sandbox "ci-gvisor-main-2"
D0410 17:27:45.078666   41858 x:0] Connecting to sandbox "ci-gvisor-main-2"
D0410 17:27:45.081075   41858 x:0] urpc: successfully marshalled 96 bytes.
I0410 17:27:45.536038   41858 x:0] Found sandbox "ci-gvisor-main-2", PID: 55373
I0410 17:27:45.536070   41858 x:0] Retrieving sandbox stacks
D0410 17:27:45.536168   41858 x:0] Stacks sandbox "ci-gvisor-main-2"
D0410 17:27:45.536176   41858 x:0] Connecting to sandbox "ci-gvisor-main-2"
D0410 17:27:45.536235   41858 x:0] urpc: successfully marshalled 36 bytes.
W0410 17:27:45.636446   41858 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-main-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-main-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer