* fix: prevent None entrance_exam_minimum_score_pct from breaking CourseOverview sync
When entrance exams are disabled in Studio, the field
`entrance_exam_minimum_score_pct` was set to `None`. This caused silent failures
when saving `CourseOverview` because the database column requires a float (NOT NULL).
This patch ensures that:
- CourseOverview sanitizes None values by falling back to
`settings.ENTRANCE_EXAM_MIN_SCORE_PCT` (default=50).
- Studio avoids writing `None` and instead applies the configured default.
Impact:
- Prevents IntegrityErrors and silent failures when updating course settings.
- Restores proper syncing between modulestore (Mongo) and CourseOverview (MySQL).
- Fixes reported issues such as display name changes not persisting and course
start dates not syncing.
Closes: https://github.com/openedx/edx-platform/issues/37319#
* refactor: clean up entrance_exam_minimum_score_pct handling
- Consolidate logic to avoid repeated assignments
- Centralize None fallback and int/float normalization
- Improve readability with inline comment and consistency with Open edX style
* test: update entrance exam deletion test to expect default min score
- Adjusted `test_entrance_exam_created_updated_and_deleted_successfully` to check for
`settings.ENTRANCE_EXAM_MIN_SCORE_PCT` instead of `None` after exam deletion
- Added handling for both int and float defaults (`/100` for integer case)
e5b497cbba