Failure here:

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20Tests%20%28dbg%29%281%29/352

[ RUN      ] MigrationTwoClientTest.MigratePrefsAndBookmarksThenModifyBookmark
Traceback (most recent call last):
  File "/b/swarming/w/ir/components/sync/tools/testserver/sync_testserver.py", line 13, in <module>
    import asyncore
ImportError: No module named asyncore