This changes 4 things:

1. Project#protected_branches_names has been renamed to
   Project#protected_branch_names.

2. Project#open_branches uses a Set for the branch names as checking
   values in a Set is faster than checking values in a (large) Array.

3. Some redundant code in Project#open_branches has been removed.

4. Project#protected_branch_names now uses #pluck instead of #map,
   removing the need for loading entire DB records into memory.

This changes Project#protected_branch? to use a query to check if a
branch is protected, instead of loading all ProtectedBranch records into
memory just to check if the list of names includes a given branch name.

This is a combination of 3 commits.

- Update the bare repositories info/attributes if the default branch is updated
- Check the diff attributes of a file before showing a diff
- Update CHANGELOG

Closes gitlab-org/gitlab-ee#506

Signed-off-by: NRémy Coutable <remy@rymai.me>

Code is based on Project Webhooks, removing deprecations and without
commits listing.

Rails' "url_helpers" method creates an anonymous Module (which a bunch
of methods) on every call. By caching the output of this method in a
dedicated method we can shave off about 10 seconds of loading time for
an issue with around 200 comments.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

This caches the output of Repository#exists? in Redis while making sure
it's flushed properly when creating new repositories, deleting them,
etc.

For the ProjectWiki tests to work I had to make ProjectWiki#create_repo!
public as testing private methods in RSpec is a bit of a pain.

The avatar logic has been moved from Project to Repository as this makes
caching easier. The logic itself in turn has been changed so that the
logo file names are cached in Redis. This cache is flushed upon pushing
a commit but _only_ if:

1. The commit was pushed to the default branch
2. The commit actually changes any of the logo files

If no branch or commit is given the cache is flushed anyway, this
ensures that calling Repository#expire_cache without any arguments still
flushes the avatar cache (e.g. this is used when removing a project).

Fixes gitlab-org/gitlab-ce#14363

The queries that are UNION'd together don't need any eager loading
(since we really only use the resulting SQL instead of having
ActiveRecord actually run the queries). By dropping any eager loaded
associations queries such as the following work instead of producing a
SQL error:

    Project.all.includes(:namespace).search('foo')

This solves the problem with caching the nil value with instance variable.
Without this the every time we ask for external_issue_tracker we built AR and potentially do SQL query

We can just use "arel_table" in these cases instead of
"SomeClass.arel_table".