Up until version 2.0.3 redis-rack included a "rake" binary that would
overwrite/hijack the one provided by Rake itself. Unfortunately the
binary provided by redis-rack would produce errors in many cases. See
https://github.com/redis-store/redis-rack/pull/34 for more info.

Closes gitaly#825

Minor changes: https://github.com/mperham/sidekiq/blob/master/Changes.md

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

Uses `list_commits_by_oid` on the CommitService, to request the needed
commits for pipelines. These commits are needed to display the user that
created the commit and the commit title.

This includes fixes for tests failing that depended on the commit
being `nil`. However, now these are batch loaded, this doesn't happen
anymore and the commits are an instance of BatchLoader.

I've followed the [upgrade guide](https://github.com/thoughtbot/factory_bot/blob/4-9-0-stable/UPGRADE_FROM_FACTORY_GIRL.md) and ran these two commands:

```
grep -e FactoryGirl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|FactoryGirl|FactoryBot|"
grep -e factory_girl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|factory_girl|factory_bot|"
```
Signed-off-by: Rémy Coutable <remy@rymai.me>

- Added an ActiveSupport (using Rails.cache) caching adapter
- Overview of the new features can be found at https://johnnunemaker.com/flippin-features-at-runtime/
- Full Changelog can be found at https://github.com/jnunemaker/flipper/blob/v0.11.0/Changelog.mdSigned-off-by: Rémy Coutable <remy@rymai.me>

Closes gitaly#808

Only the Gemfile.lock was updated before.

+ change string concatenation to help with GC pressure.
+ fix metric producing incompatible label sets

Closes gitaly#780

Closes gitaly#737

Changes since 4.2.8:

- [No change in ActionMailer](https://github.com/rails/rails/blob/v4.2.10/actionmailer/CHANGELOG.md)
- [1 change and 1 regression fix in ActionPack](https://github.com/rails/rails/blob/v4.2.10/actionpack/CHANGELOG.md)
- [No change in ActiveModel](https://github.com/rails/rails/blob/v4.2.10/activemodel/CHANGELOG.md)
- [7 fixes in ActiveRecord](https://github.com/rails/rails/blob/v4.2.10/activerecord/CHANGELOG.md)
- [5 fixes in ActiveSupport](https://github.com/rails/rails/blob/v4.2.10/activesupport/CHANGELOG.md)
- [No change in Railties](https://github.com/rails/rails/blob/v4.2.10/railties/CHANGELOG.md)
Signed-off-by: Rémy Coutable <remy@rymai.me>

See https://gitlab.com/gitlab-org/gitlab-ce/issues/40690 and
https://github.com/mbleigh/seed-fu/issues/123 for details.
Signed-off-by: Rémy Coutable <remy@rymai.me>

[ci skip]

After installing a new gem, batch-loader, a construct can be used to
queue data to be fetched in bulk. The gem was also introduced in both
gitlab-org/gitlab-ce!14680 and gitlab-org/gitlab-ce!14846, but those mrs
are not merged yet.

For the generation of diffs, both the old blob and the new blob need to
be loaded. This for every file in the diff, too. Now we collect all
these so we do 1 fetch. Three `.allow_n_plus_1_calls` have been removed,
which I expect to be valid, but this needs to be confirmed by a full CI
run.

Possibly closes:
- https://gitlab.com/gitlab-org/gitlab-ce/issues/37445
- https://gitlab.com/gitlab-org/gitlab-ce/issues/37599
- https://gitlab.com/gitlab-org/gitlab-ce/issues/37431

This solves a problem where Gitaly connections through Unix sockets
would not work when a proxy was configures, even if a no_proxy setting
was specified

Closes gitaly#673

We also unify conversions from and to `Gitaly::User`s in the
`Gitlab::Git::User` class.