[flaky] tests/vibe.core.net.1452 test

[wilzbach]

The test fails spuriously on Buildkite

+ echo '[INFO] Running test tests/vibe.core.net.1452.d'
--
  | [INFO] Running test tests/vibe.core.net.1452.d
  | + dub --temp-build --compiler=dmd --single tests/vibe.core.net.1452.d
  | Performing "debug" build using dmd for x86_64.
  | taggedalgebraic 0.11.8: target for configuration "library" is up to date.
  | eventcore 0.8.48: target for configuration "epoll" is up to date.
  | stdx-allocator 2.77.5: target for configuration "library" is up to date.
  | vibe-core 1.8.1: building configuration "epoll"...
  | source/vibe/core/channel.d(110,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/channel.d(114,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/concurrency.d(508,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/concurrency.d(524,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/core.d(915,1): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/core.d(1149,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(368,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(372,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(377,4): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/internal/freelistref.d(193,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/internal/freelistref.d(229,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | test ~master: building configuration "application"...
  | source/vibe/core/core.d(915,1): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/core.d(1149,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/concurrency.d(508,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/concurrency.d(524,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(368,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(372,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/core/net.d(377,4): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/internal/freelistref.d(193,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | source/vibe/internal/freelistref.d(229,3): Deprecation: Usage of the `body` keyword is deprecated. Use `do` instead.
  | Linking...
  | To force a rebuild of up-to-date targets, run again with --force.
  | Running ../tmp/.dub/build/test-~master/application-debug-linux.posix-x86_64-dmd_2090-CBDDAB1D7A17049C6FA638340B42A844/test
  | object.Exception@source/vibe/core/net.d(229): Failed to connect to [2606:2800:220:1:248:1893:25c8:1946]:443: refused
  | ----------------
  | /var/lib/buildkite-agent/builds/ci-agent-d5f25bab-6349-43ee-a2ba-15e34ea6240b-2/dlang/dmd/build/distribution/bin/../imports/std/exception.d:515 pure @safe void std.exception.bailOut!(Exception).bailOut(immutable(char)[], ulong, scope const(char)[]) [0x646c16]
  | /var/lib/buildkite-agent/builds/ci-agent-d5f25bab-6349-43ee-a2ba-15e34ea6240b-2/dlang/dmd/build/distribution/bin/../imports/std/exception.d:436 pure @safe bool std.exception.enforce!().enforce!(bool).enforce(bool, lazy const(char)[], immutable(char)[], ulong) [0x646b92]
  | source/vibe/core/net.d:229 @trusted vibe.core.net.TCPConnection vibe.core.net.connectTCP(vibe.core.net.NetworkAddress, vibe.core.net.NetworkAddress, core.time.Duration).__lambda5() [0x61dd87]
  | source/vibe/core/net.d:202 @safe vibe.core.net.TCPConnection vibe.core.net.connectTCP(vibe.core.net.NetworkAddress, vibe.core.net.NetworkAddress, core.time.Duration) [0x61db7d]
  | source/vibe/core/net.d:185 @safe vibe.core.net.TCPConnection vibe.core.net.connectTCP(immutable(char)[], ushort, immutable(char)[], ushort, core.time.Duration) [0x61da61]
  | tests/vibe.core.net.1452.d:18 test.C test.C.__ctor() [0x6183e5]
  | tests/vibe.core.net.1452.d:29 _Dmain [0x61846b]
  | Program exited with code 1

See also: https://buildkite.com/dlang/dmd/builds/11209#3fdfa23a-5c89-49a6-b701-b68626778731