Project setting to "Allow merge before pipeline(s) complete"

Release notes

Sometimes it is necessary to bypass Merge Results pipelines (if enabled) and Merge Trains (if enabled) when you have a high-priority merge request (for example, a critical patch) that must be merged urgently. But the consequence of having a Merge immediately button is the increased risk of merging a breaking change into your target branch. Now project owners/maintainers can disable this default behavior at the project-level by unchecking Allow merge before pipelines completes.

Problem to solve

NOTE: This feature is an interim solution for a merge requests priority2 ~bug #225488 (closed).

As a project maintainer or owner, I want the ability to disable Merge immediately, so I can reduce the risk of merging a MR that breaks the main/target branch.

When Merge Results pipelines is enabled and/or Merge Trains is enabled, the merge button has an alternate path to Merge immediately (see docs) which can potentially result in a merge that breaks the target branch IF the state of the target branch has changed AFTER the merge results pipeline succeeded (making whatever it validated outdated).

Intended users

• Project Owner/Maintainer

User experience goal

The user should have a project setting to configure (enable/disable) Merge immediately button/capability.

Proposal

At project Settings > General > Merge requests (expanded) > Merge options (section):

• Add new option is Allow merge before pipelines complete checkbox that is placed directly above the option/checkbox to Automatically resolve merge request diff discussions when they become outdated (refer to "Screenshot of existing options" below).
• This new option should have the following copy/text:
  • Allow merge before pipeline(s) complete
    Merge requests can be merged before pipeline(s) complete by using the Merge immediately button, or an API call.
    
• This new option is enabled by default (checkbox is checked for all projects).
• If this new option is disabled, then:
  • Merge immediately button is hidden
  • Merge via API endpoint for Accept MR is not allowed

Screenshot of existing options