Please describe the problem.
in recent builds eg
adjusted branch subtree regression: FAIL (1.26s)
Test.hs:1675:
a/b/x/y missing from master after adjusted branch sync
Use -p '/adjusted branch subtree regression/' to rerun this test only.
may be more
This was caused by 2c86651180d5c8648b8244be894c26bc98a6c334 and so I've reverted that commit for now.
Leaving this bug open because that commit was an important optimisation and needs to be fixed and reapplied.