change test_assign_bad_index_ref reference a soft-deleted case

rather than actually deleted case
Add checkpoints for debugging
Raise a proper AttributeError if method not found
Merge branch 'test_assign_bad_index_ref' into explicit_case_processing
Merge pull request #4041 from dimagi/rule-debugging

Add checkpoints for debugging
Merge pull request #4042 from dimagi/attribute-error

Raise a proper AttributeError if method not found
move process signals outside transaction

and save xform a second time, only if there are errors
Merge remote-tracking branch 'origin/explicit_case_processing' into autostaging
Merge remote-tracking branch 'origin/auto-gps+schedule' into autostaging
Merge remote-tracking branch 'origin/auto-gps' into autostaging
Merge remote-tracking branch 'origin/es_none_type' into autostaging
Merge remote-tracking branch 'origin/hq-dropdown' into autostaging
Merge branch 'refactor-domain-copy2' into autostaging
Merge remote-tracking branch 'origin/logos' into autostaging
Merge remote-tracking branch 'origin/vellum-requirejs' into autostaging
Merge branch 'emwf-refactor' into autostaging
Merge remote-tracking branch 'origin/real-project-spaces' into autostaging
Merge remote-tracking branch 'origin/archive-to-deactivate' into autostaging
Merge remote-tracking branch 'origin/subscription-no-contact-info' into autostaging
Merge branch 'opm' into autostaging