upgrade: speed up when we have only nodemap to downgrade

The test change is wrong.
13 jobs for topic/default/upgrade-refactor in 33 minutes and 31 seconds (queued for 49 seconds)
Status Job ID Name Coverage
  Tests
passed #166530
checks-py2

00:03:40

passed #166531
checks-py3

00:03:22

passed #166532
rust-cargo-test-py2

00:02:25

passed #166533
rust-cargo-test-py3

00:03:30

passed #166534
test-py2

00:29:02

passed #166540
test-py2-chg

00:25:49

passed #166536
test-py2-pure

00:20:22

passed #166538
test-py2-rust

00:21:33

passed #166535
test-py3

00:24:03

passed #166541
test-py3-chg

00:15:46

passed #166537
test-py3-pure

00:14:32

passed #166539
test-py3-rust

00:23:10

 
  Phabricator
passed #166542
phabricator-refresh

00:00:22