flaky session test

[marten-seemann]

Failure in Spec Teardown (AfterEach) [0.024 seconds]
Session [AfterEach]
/home/travis/gopath/src/github.com/lucas-clemente/quic-go/session_test.go:44
  sending packets
  /home/travis/gopath/src/github.com/lucas-clemente/quic-go/session_test.go:1006
    sends packets
    /home/travis/gopath/src/github.com/lucas-clemente/quic-go/session_test.go:1034
    missing call(s) to *quic.MockPacker.PackPacket() /home/travis/gopath/src/github.com/lucas-clemente/quic-go/session_test.go:1039
    /home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/leafnodes/runner.go:113
    Full Stack Trace
    github.com/onsi/ginkgo/internal/leafnodes.(*runner).runSync(0xc0004b62a0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/leafnodes/runner.go:113 +0xe0
    github.com/onsi/ginkgo/internal/leafnodes.(*runner).run(0xc0004b62a0, 0x17fb230, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/leafnodes/runner.go:64 +0x108
    github.com/onsi/ginkgo/internal/leafnodes.(*SetupNode).Run(0xc0000103c0, 0x11945a0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/leafnodes/setup_nodes.go:15 +0x88
    github.com/onsi/ginkgo/internal/spec.(*Spec).runSample.func1(0xc000237608, 0xc0004daf00, 0x11945a0, 0xc000084900)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/spec/spec.go:180 +0x49a
    github.com/onsi/ginkgo/internal/spec.(*Spec).runSample(0xc0004daf00, 0x0, 0x11945a0, 0xc000084900)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/spec/spec.go:218 +0x774
    github.com/onsi/ginkgo/internal/spec.(*Spec).Run(0xc0004daf00, 0x11945a0, 0xc000084900)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/spec/spec.go:138 +0x168
    github.com/onsi/ginkgo/internal/specrunner.(*SpecRunner).runSpec(0xc00044d680, 0xc0004daf00, 0x0)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/specrunner/spec_runner.go:200 +0x173
    github.com/onsi/ginkgo/internal/specrunner.(*SpecRunner).runSpecs(0xc00044d680, 0x1)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/specrunner/spec_runner.go:170 +0x217
    github.com/onsi/ginkgo/internal/specrunner.(*SpecRunner).Run(0xc00044d680, 0x8)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/specrunner/spec_runner.go:66 +0x141
    github.com/onsi/ginkgo/internal/suite.(*Suite).Run(0xc0000de230, 0x7f1c105a1e50, 0xc00038c400, 0x1034607, 0xa, 0xc0002d7ce0, 0x1, 0x1, 0x11a5520, 0xc000084900, ...)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/internal/suite/suite.go:62 +0x6a0
    github.com/onsi/ginkgo.RunSpecsWithCustomReporters(0x1194be0, 0xc00038c400, 0x1034607, 0xa, 0xc000060ed8, 0x1, 0x1, 0x12e8490)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/ginkgo_dsl.go:226 +0x339
    github.com/onsi/ginkgo.RunSpecs(0x1194be0, 0xc00038c400, 0x1034607, 0xa, 0x0)
    	/home/travis/gopath/pkg/mod/github.com/onsi/ginkgo@v1.12.0/ginkgo_dsl.go:207 +0x24e
    github.com/lucas-clemente/quic-go.TestQuicGo(0xc00038c400)
    	/home/travis/gopath/src/github.com/lucas-clemente/quic-go/quic_suite_test.go:15 +0xf9
    testing.tRunner(0xc00038c400, 0x10632f0)
    	/home/travis/.gimme/versions/go1.13.10.linux.amd64/src/testing/testing.go:909 +0x19a
    created by testing.(*T).Run
    	/home/travis/.gimme/versions/go1.13.10.linux.amd64/src/testing/testing.go:960 +0x652