Implement new preparing internal merge_status
What does this MR do?
When we check if MR is mergeable we also check the CI pipeline. Since we are creating the pipeline asynchronously via
MergeRequests::AfterCreateService, there's a possible race condition wherein the pipeline isn't created yet but we already checked if MR is mergeable. That can result to inaccurate outcome.
To ensure that whenever we check if MR is mergeable, we introduced a new internal state called preparing. When the MR is in this state, it means it's still being prepared (e.g. creating a pipeline) and it's not mergeable.
Once the preparation is finished, we mark the MR as unchecked so we can check its mergeability when the user views the MR page.
Does this MR meet the acceptance criteria?
Conformity
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Changelog entry -
Documentation (if required) -
Code review guidelines -
Merge request performance guidelines -
Style guides -
Database guides -
Separation of EE specific content
Availability and Testing
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Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process. -
Tested in all supported browsers -
Informed Infrastructure department of a default or new setting change, if applicable per definition of done
Security
If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:
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Label as security and @ mention @gitlab-com/gl-security/appsec -
The MR includes necessary changes to maintain consistency between UI, API, email, or other methods -
Security reports checked/validated by a reviewer from the AppSec team
Related to #291012 (closed)