When I attempt to restore a course exported from Moodle 2.6.4 into Moodle 2.7.3 or Moodle 2.6.4 (a copy of the install that was used to create the backup), it fails with a "Column 'gradingstrategy' cannot be null...mdl_scheduler" error.

Error generated in Moodle 2.6.4:
Debug info: Column 'gradingstrategy' cannot be null
INSERT INTO mdl_scheduler (name,intro,introformat,schedulermode,reuseguardtime,defaultslotduration,allownotifications,staffrolename,teacher,scale,gradingstrategy,timemodified,course) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?)
[array (
0 => 'Conference Sign-Up',
1 => '<p>Directions</p>',
2 => '1',
3 => 'onetime',
4 => '24',
5 => '15',
6 => '0',
7 => '',
8 => 0,
9 => '0',
10 => NULL,
11 => 1416509304,
12 => 4,
)]
Error code: dmlwriteexception
Stack trace:
line 446 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 1080 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1122 of /lib/dml/mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
line 55 of /mod/scheduler/backup/moodle2/restore_scheduler_stepslib.php: call to mysqli_native_moodle_database->insert_record()
line 137 of /backup/util/plan/restore_structure_step.class.php: call to restore_scheduler_activity_structure_step->process_scheduler()
line 103 of /backup/util/helper/restore_structure_parser_processor.class.php: call to restore_structure_step->process()
line 151 of /backup/util/xml/parser/processors/grouped_parser_processor.class.php: call to restore_structure_parser_processor->dispatch_chunk()
line 91 of /backup/util/helper/restore_structure_parser_processor.class.php: call to grouped_parser_processor->postprocess_chunk()
line 148 of /backup/util/xml/parser/processors/simplified_parser_processor.class.php: call to restore_structure_parser_processor->postprocess_chunk()
line 92 of /backup/util/xml/parser/processors/progressive_parser_processor.class.php: call to simplified_parser_processor->process_chunk()
line 186 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser_processor->receive_chunk()
line 274 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->publish()
line ? of unknownfile: call to progressive_parser->end_tag()
line 175 of /backup/util/xml/parser/progressive_parser.class.php: call to xml_parse()
line 154 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->parse()
line 110 of /backup/util/plan/restore_structure_step.class.php: call to progressive_parser->process()
line 181 of /backup/util/plan/base_task.class.php: call to restore_structure_step->execute()
line 192 of /backup/moodle2/restore_activity_task.class.php: call to base_task->execute()
line 177 of /backup/util/plan/base_plan.class.php: call to restore_activity_task->execute()
line 167 of /backup/util/plan/restore_plan.class.php: call to base_plan->execute()
line 333 of /backup/controller/restore_controller.class.php: call to restore_plan->execute()
line 184 of /backup/util/ui/restore_ui.class.php: call to restore_controller->execute_plan()
line 99 of /backup/restore.php: call to restore_ui->execute()

Error generated in Moodle 2.7.3:
Debug info: Column 'gradingstrategy' cannot be null
INSERT INTO mdl_scheduler (name,intro,introformat,schedulermode,reuseguardtime,defaultslotduration,allownotifications,staffrolename,scale,gradingstrategy,timemodified,course) VALUES(?,?,?,?,?,?,?,?,?,?,?,?)
[array (
0 => 'Conference Sign-Up',
1 => '<p>Please sign-up for your conference here. Remember, missing a conference equals missing a class session. </p>',
2 => '1',
3 => 'onetime',
4 => '24',
5 => '15',
6 => '0',
7 => '',
8 => '0',
9 => NULL,
10 => 1416509304,
11 => 2,
)]
Error code: dmlwriteexception
Stack trace:
line 446 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 1164 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1210 of /lib/dml/mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
line 54 of /mod/scheduler/backup/moodle2/restore_scheduler_stepslib.php: call to mysqli_native_moodle_database->insert_record()
line 137 of /backup/util/plan/restore_structure_step.class.php: call to restore_scheduler_activity_structure_step->process_scheduler()
line 103 of /backup/util/helper/restore_structure_parser_processor.class.php: call to restore_structure_step->process()
line 151 of /backup/util/xml/parser/processors/grouped_parser_processor.class.php: call to restore_structure_parser_processor->dispatch_chunk()
line 91 of /backup/util/helper/restore_structure_parser_processor.class.php: call to grouped_parser_processor->postprocess_chunk()
line 148 of /backup/util/xml/parser/processors/simplified_parser_processor.class.php: call to restore_structure_parser_processor->postprocess_chunk()
line 92 of /backup/util/xml/parser/processors/progressive_parser_processor.class.php: call to simplified_parser_processor->process_chunk()
line 190 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser_processor->receive_chunk()
line 278 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->publish()
line ? of unknownfile: call to progressive_parser->end_tag()
line 179 of /backup/util/xml/parser/progressive_parser.class.php: call to xml_parse()
line 158 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->parse()
line 110 of /backup/util/plan/restore_structure_step.class.php: call to progressive_parser->process()
line 181 of /backup/util/plan/base_task.class.php: call to restore_structure_step->execute()
line 192 of /backup/moodle2/restore_activity_task.class.php: call to base_task->execute()
line 177 of /backup/util/plan/base_plan.class.php: call to restore_activity_task->execute()
line 167 of /backup/util/plan/restore_plan.class.php: call to base_plan->execute()
line 333 of /backup/controller/restore_controller.class.php: call to restore_plan->execute()
line 184 of /backup/util/ui/restore_ui.class.php: call to restore_controller->execute_plan()
line 107 of /backup/restore.php: call to restore_ui->execute()