All tests are pretty flaky

[PapaTutuWawa]

They very occasionally fail for the same reason:

  Instance of 'UnknownSignedPrekeyException'
  package:omemo_dart/src/omemo/sessionmanager.dart 185:7  OmemoSessionManager._addSessionFromKeyExchange
  ===== asynchronous gap ===========================
  package:omemo_dart/src/omemo/sessionmanager.dart 347:7  OmemoSessionManager.decryptMessage
  ===== asynchronous gap ===========================
  test/omemo_test.dart 254:24                             main.<fn>

[PapaTutuWawa]

bobSpkId: 2763074306
aliceSpkId: 1342758128
kex.spkId: 77, device.spkId: 569114685, device.oldSpkId: 2214281293
00:03 +27 -1: test/omemo_test.dart: Test accepting a session with an old SPK [E]                          
  Instance of 'UnknownSignedPrekeyException'
  package:omemo_dart/src/omemo/sessionmanager.dart 191:7  OmemoSessionManager._addSessionFromKeyExchange
  ===== asynchronous gap ===========================
  package:omemo_dart/src/omemo/sessionmanager.dart 351:7  OmemoSessionManager.decryptMessage
  ===== asynchronous gap ===========================
  test/omemo_test.dart 333:24       

[PapaTutuWawa]

I think I fixed it. Verified by running

for i in {0..99}; do
	echo "RUN $i"
	dart test -j 8
	[[ ! $? = 0 ]] && exit 1
done

[PapaTutuWawa]

Hopefully fixed by 438012d.