Extract 'experimental.evolution' = createmarkers as
'experimental.evolution.createmarkers'.
We keep the new option in the 'experimental.evolution' namespace in order to
stay coherent with other options ('experimental.evolution.bundle-obsmarker'
and 'experimental.evolution.track-operation') ease the renaming as possibly
'evolution.createmarkers'.
Differential Revision: https://phab.mercurial-scm.org/D1149
This test has gotten so large that running it can exceed the normal timeout on
systems under load (like if we're running all the tests in parallel). This patch
splits the test cleanly in half.
Differential Revision: https://phab.mercurial-scm.org/D694