The problem is that we often go via a diff object constructed from the diffs
stored in the DB. Those diffs, by definition, don't overflow, so we don't have
access to the 'correct' `real_size` - that is stored on the MR diff object
iself.

This reverts commit e00fb2bdc2090e9cabeb1eb35a2672a882cc96e9.

# Conflicts:
#	.rubocop.yml
#	.rubocop_todo.yml
#	lib/gitlab/ci/config/entry/global.rb
#	lib/gitlab/ci/config/entry/jobs.rb
#	spec/lib/gitlab/ci/config/entry/factory_spec.rb
#	spec/lib/gitlab/ci/config/entry/global_spec.rb
#	spec/lib/gitlab/ci/config/entry/job_spec.rb
#	spec/lib/gitlab/ci/status/build/factory_spec.rb
#	spec/lib/gitlab/incoming_email_spec.rb

This reverts commit cb10b725c8929b8b4460f89c9d96c773af39ba6b.

commits from the other repository. We'll cleanup
the tmp ref after we're done with our business.

when we care only about the number of commits

We do not have to instantiate all objects in this case.

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6658#note_17190236

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

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

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

Customers running old versions of GitLab may have MergeRequestDiffs with
the text ["--broken diff"] due to text generated by gitlab_git 1.0.3.
To avoid the Error 500, verify that each element is a type that gitlab_git
will accept before attempting to create a DiffCollection.

Closes #20776

Closes #22438

This way we could also show pipelines from commits which
were discarded due to a force push.

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

* remove ref fetch (we do it during creation anyway)
* remove safe_head_commit_sha for diff compare (do not depend on the source branch)
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

* Add MergeRequestDiff#latest?
* Remove unnecessary variable assignment
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

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

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

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

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

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

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

Speedup DiffNote#active? on discussions, preloading noteables and avoid touching git repository to return diff_refs when possible

- Preloading noteable we share the same noteable instance when more than one 
discussion refers to the same noteable.
- Any other call to that object that is cached in that object will be for any 
discussion.
- In those cases where merge_request_diff has all the sha stored to build a diff_refs get that 
diff_refs using directly those sha instead accessing to the git repository to first get the 
commits and later the sha.

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