Progress bar tests are still racy
Job #5177 failed for 23a275b5:
The relevant fragment was:
FAIL: update_test.go:204: updateSuite.TestUpdateCancelledLater
update_test.go:247:
c.Check(scan.Text(), Equals, "kind:system-update, state:running, progress:50%")
... obtained string = "kind:system-update, state:running, progress:0%"
... expected string = "kind:system-update, state:running, progress:50%"
OOPS: 36 passed, 1 FAILED
--- FAIL: Test (1.30s)
This failed on Raspberry Pi 4. Perhaps stress-testing this particular unit test on an artificially slowed-down system would be sufficient to reproduce the problem.