flutter ShellTest.UserTagSetOnStartup test regression on user tag change

[aam]

Seemingly after https://dart.googlesource.com/sdk/+/1b6700115dc5308f3d08d858dbaa8cec1735cfcf flutter hh is failing:

logs

[167/396] ShellTest.UserTagSetOnStartup (233 ms)
[INFO:flutter/testing/test_timeout_listener.cc(75)] Test timeout of 300 seconds per test case will be enforced.
�[0;33mNote: Google Test filter = ShellTest.UserTagSetOnStartup
�[m�[0;32m[==========] �[mRunning 1 test from 1 test suite.
�[0;32m[----------] �[mGlobal test environment set-up.
�[0;32m[----------] �[m1 test from ShellTest
�[0;32m[ RUN      ] �[mShellTest.UserTagSetOnStartup
../../flutter/shell/common/shell_unittests.cc:3697: Failure
Value of: Dart_IdentityEquals(current_tag, startup_tag)
  Actual: false
Expected: true

�[0;31m[  FAILED  ] �[mShellTest.UserTagSetOnStartup (34 ms)
�[0;32m[----------] �[m1 test from ShellTest (34 ms total)

�[0;32m[----------] �[mGlobal test environment tear-down
�[0;32m[==========] �[m1 test from 1 test suite ran. (34 ms total)
�[0;32m[  PASSED  ] �[m0 tests.
�[0;31m[  FAILED  ] �[m1 test, listed below:
�[0;31m[  FAILED  ] �[mShellTest.UserTagSetOnStartup

 1 FAILED TEST
[167/396] ShellTest.UserTagSetOnStartup returned/aborted with exit code 1 (233 ms)
[168/396] ShellTest.RasterizerScreenshot (233 ms)
[169/396] ShellTest.RasterizerScreenshot (233 ms)
[170/396] ShellTest.NotifyIdleRejectsPastAndNearFuture (233 ms)
[171/396] ShellTest.UserTagSetOnStartup (233 ms)
[INFO:flutter/testing/test_timeout_listener.cc(75)] Test timeout of 300 seconds per test case will be enforced.
�[0;33mNote: Google Test filter = ShellTest.UserTagSetOnStartup
�[m�[0;32m[==========] �[mRunning 1 test from 1 test suite.
�[0;32m[----------] �[mGlobal test environment set-up.
�[0;32m[----------] �[m1 test from ShellTest
�[0;32m[ RUN      ] �[mShellTest.UserTagSetOnStartup
../../flutter/shell/common/shell_unittests.cc:3697: Failure
Value of: Dart_IdentityEquals(current_tag, startup_tag)
  Actual: false
Expected: true

�[0;31m[  FAILED  ] �[mShellTest.UserTagSetOnStartup (37 ms)
�[0;32m[----------] �[m1 test from ShellTest (37 ms total)

�[0;32m[----------] �[mGlobal test environment tear-down
�[0;32m[==========] �[m1 test from 1 test suite ran. (37 ms total)
�[0;32m[  PASSED  ] �[m0 tests.
�[0;31m[  FAILED  ] �[m1 test, listed below:
�[0;31m[  FAILED  ] �[mShellTest.UserTagSetOnStartup

 1 FAILED TEST