Grand Central has a scheduler running. The scheduler does not support sharing a job store, so we must wait for one GC to stop before starting another one.
Checklist
[x] Relevant changes are reflected in CHANGES.rst - no need, changes unreleased.
[x] Added or changed code is covered by tests - implicitly
[x] Documentation has been updated if necessary
[x] Changed code does not contain any breaking changes (or this is a major version change)
Summary of changes
Grand Central has a scheduler running. The scheduler does not support sharing a job store, so we must wait for one GC to stop before starting another one.
Checklist
CHANGES.rst- no need, changes unreleased.