Merge branch 'fix/builds-api-builds-for-commit-search' into 'master'

Find all builds for commit if there are multiple pipelines for it

## What does this MR do?

This MR fixes a builds API. When multiple pipelines were triggered for a commit, then API returned builds only from the last pipeline.

## What are the relevant issue numbers?

Closes #18912  
Closes #19243 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4849

1 files changed, 5 insertions, 0 deletions

diff --git a/doc/api/builds.md b/doc/api/builds.md
index de998944352..2adea11247e 100644
--- a/doc/api/builds.md
+++ b/doc/api/builds.md
@@ -107,6 +107,11 @@ Example of response
 
 Get a list of builds for specific commit in a project.
 
+This endpoint will return all builds, from all pipelines for a given commit.
+If the commit SHA is not found, it will respond with 404, otherwise it will
+return an array of builds (an empty array if there are no builds for this
+particular commit).
+
 ```
 GET /projects/:id/repository/commits/:sha/builds
 ```