Unstable order of pipelines for a commit

Summary

A list of pipelines for a commit is unstable i.e., not sorted. (GitLab CE/EE 8.13 through 8.15)

Steps to reproduce

1. On a GitLab CI-enabled project, for a single commit you have to trigger a pipeline many times (3-20 times) so that the commit has several pipelines.
2. Have access to https://gitlab.com/NAMESPACE/PROJECT/commit/REF/pipelines or your GitLab instance. e.g., tnir/centos-for-ci@2a76954b

Expected behavior

A list of pipelines for a commit must be sorted in pipeline's created_at as builds and pipelines in other pages.

Actual behavior

A list of pipelines for a commit is not always sorted in pipeline's created_at, unlike builds and pipelines in other pages.

Relevant logs and/or screenshots

tnir/centos-for-ci@2a76954b

Output of checks

This bug happens on GitLab.com too.

Results of GitLab application Check

n/a

Results of GitLab environment info

n/a

Possible fixes

Specify the sort order for pipelines for a commit.