1. The main implementation is in the `ProtectedBranch` model. The
wildcard is converted to a Regex and compared. This has been tested
thoroughly.
- While `Project#protected_branch?` is the main entry point,
`project#open_branches` and
`project#developers_can_push_to_protected_branch?`
have also been modified to work with wildcard protected branches.
- The regex is memoized (within the `ProtectedBranch` instance)
2. Improve the performance of `Project#protected_branch?`
- This method is called from `Project#open_branches` once _per branch_
in the project, to check if that branch is protected or not.
- Before, `#protected_branch?` was making a database call every
time it was invoked (in the above case, that amounts to once
per branch), which is expensive.
- This commit caches the list of protected branches in memory, which
reduces the number of database calls down to 1.
- A downside to this approach is that `#protected_branch?` _could_
return a stale value (due to the caching), but this is
an acceptable tradeoff.
3. Remove the (now) unused `Project#protected_branch_names` method.
- This was previously used to check for protected branch status.
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