utility: deal with having multiple

When a revision has multiple prune obsolescence markers, it's thought
to be a split, and the way we try to deal with splits currently crashes.

--HG--
branch : stable
7 jobs for topic/stable/evolve_multiprune in 4 minutes and 29 seconds
Status Name Job ID Coverage
  Test
passed doc #72831

00:00:23

passed flake8 #72825

00:00:34

manual pytype #72826
allowed to fail manual
failed tests-py2-cext #72827

00:03:25

failed tests-py2-pure #72828

00:04:12

failed tests-py3-cext #72829

00:02:21

failed tests-py3-pure #72830

00:04:27

 
Name Stage Failure
failed
tests-py3-pure Test
Failed test-topic-flow-single-head.t: output changed
Failed test-topic-push-concurrent-on.t: output changed
Failed test-topic-push.t: output changed
Failed test-topic-tutorial.t: output changed
Failed test-unstability-resolution-result.t: output changed
Failed test-wireproto.t: output changed
# Ran 190 tests, 0 skipped, 31 failed.
python hash seed: 338716879
ERROR: Job failed: exit code 1
failed
tests-py3-cext Test
Failed test-topic-flow-single-head.t: output changed
Failed test-topic-push-concurrent-on.t: output changed
Failed test-topic-push.t: output changed
Failed test-topic-tutorial.t: output changed
Failed test-unstability-resolution-result.t: output changed
Failed test-wireproto.t: output changed
# Ran 190 tests, 0 skipped, 31 failed.
python hash seed: 1923845656
ERROR: Job failed: exit code 1
failed
tests-py2-pure Test
Failed test-topic-flow-single-head.t: output changed
Failed test-topic-push-concurrent-on.t: output changed
Failed test-topic-push.t: output changed
Failed test-topic-tutorial.t: output changed
Failed test-unstability-resolution-result.t: output changed
Failed test-wireproto.t: output changed
# Ran 190 tests, 0 skipped, 31 failed.
python hash seed: 4164303623
ERROR: Job failed: exit code 1
failed
tests-py2-cext Test
Failed test-topic-flow-single-head.t: output changed
Failed test-topic-push-concurrent-on.t: output changed
Failed test-topic-push.t: output changed
Failed test-topic-tutorial.t: output changed
Failed test-unstability-resolution-result.t: output changed
Failed test-wireproto.t: output changed
# Ran 190 tests, 0 skipped, 31 failed.
python hash seed: 1482946698
ERROR: Job failed: exit code 1