Fix 500 error in Commits API when the repository is empty

What does this MR do and why?

Contributes to #452488 (closed)

Problem

Gitaly started returning an internal error, when the user requests commits of the empty repository: gitaly!6590 (merged). Rails doesn't handle it and returns a 500 error.

Solution

Add a temporary handler for this error, before the Gitaly code is updated.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

1. Create a project with an empty repository (without README.md)
2. Visit http://127.0.0.1:3000/api/v4/projects/<project_id>/repository/commits
3. You should see an empty array response instead of an internal error.

changed milestone to %16.11

added backend bugfunctional groupsource code labels

assigned to @vyaklushin

added typebug label

added Category:Source Code Management devopscreate sectiondev labels

mentioned in issue #452488 (closed)

Reviewer roulette

Category	Reviewer	Maintainer
backend	@praba.m7n (UTC+2, same timezone as author)	@rymai (UTC+2, same timezone as author)

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Generated by Danger

added 1 commit

• 7d24d374 - Fix 500 error in Commits API when the repository is empty

Compare with previous version

Hi @Quintasan! Can you please review this fix?

requested review from @Quintasan

approved this merge request

requested review from @pedropombeiro

added pipeline:mr-approved label

@Quintasan, thanks for approving this merge request.

This is the first time the merge request has been approved. To ensure we don't only run predictive pipelines, and we don't break master, a new pipeline will be started shortly.

Please wait for the pipeline to start before resolving this discussion and set auto-merge for the new pipeline. See merging a merge request for more details.

resolved all threads

enabled an automatic merge when the pipeline for 27bbafc2 succeeds

E2E Test Result Summary

allure-report-publisher generated test report!

e2e-test-on-gdk: test report for 02e353a5

expand test summary

+------------------------------------------------------------------+
|                          suites summary                          |
+-------------+--------+--------+---------+-------+-------+--------+
|             | passed | failed | skipped | flaky | total | result |
+-------------+--------+--------+---------+-------+-------+--------+
| Plan        | 51     | 0      | 2       | 0     | 53    | ✅     |
| Verify      | 35     | 0      | 1       | 0     | 36    | ✅     |
| Package     | 24     | 0      | 6       | 0     | 30    | ✅     |
| Govern      | 66     | 0      | 0       | 0     | 66    | ✅     |
| Create      | 77     | 0      | 9       | 0     | 86    | ✅     |
| Data Stores | 31     | 0      | 0       | 0     | 31    | ✅     |
| Monitor     | 7      | 0      | 0       | 0     | 7     | ✅     |
| Release     | 5      | 0      | 0       | 0     | 5     | ✅     |
| Analytics   | 2      | 0      | 0       | 0     | 2     | ✅     |
| Manage      | 0      | 0      | 1       | 0     | 1     | ➖     |
+-------------+--------+--------+---------+-------+-------+--------+
| Total       | 298    | 0      | 19      | 0     | 317   | ✅     |
+-------------+--------+--------+---------+-------+-------+--------+

e2e-package-and-test: test report for 02e353a5

expand test summary

+------------------------------------------------------------------+
|                          suites summary                          |
+-------------+--------+--------+---------+-------+-------+--------+
|             | passed | failed | skipped | flaky | total | result |
+-------------+--------+--------+---------+-------+-------+--------+
| Create      | 570    | 0      | 66      | 10    | 636   | ✅     |
| Plan        | 8      | 0      | 0       | 0     | 8     | ✅     |
| Data Stores | 4      | 0      | 0       | 0     | 4     | ✅     |
| Govern      | 6      | 0      | 0       | 0     | 6     | ✅     |
| Monitor     | 8      | 0      | 0       | 0     | 8     | ✅     |
| Package     | 0      | 0      | 2       | 0     | 2     | ➖     |
+-------------+--------+--------+---------+-------+-------+--------+
| Total       | 596    | 0      | 68      | 10    | 664   | ✅     |
+-------------+--------+--------+---------+-------+-------+--------+

aborted the automatic merge because source branch was updated

added 1 commit

• 02e353a5 - Add a test to fix undercoverage failure

Compare with previous version

reset approvals from @Quintasan by pushing to the branch

Hi @pedropombeiro! Can you please review this fix and set an auto-merge again?

The previous attempt failed because of rspec::undercoverage test. I've added a new test to fix this failure.

approved this merge request

enabled an automatic merge when the pipeline for 78b98a71 succeeds

merged

mentioned in commit 457909e1

mentioned in incident gitlab-org/quality/engineering-productivity/review-apps-broken-incidents#1520 (closed)

added workflowstaging-canary label

added workflowcanary label and removed workflowstaging-canary label

@vyaklushin this is somewhat dangerous as this message matches all unknown error that might cause listing commits to fail. While there is a regression in #452488 (closed), this workaround will cause most errors to be ignored. I think we should prioritize fixin the actual issue in Gitaly and revert this as this leads to incorrect results.

Keeping the new tests would be very useful though, so let's keep them but just remove this single error handling case.

added workflowstaging label and removed workflowcanary label

added workflowproduction label and removed workflowstaging label

added workflowpost-deploy-db-staging label and removed workflowproduction label

added releasedcandidate label

mentioned in merge request !148979 (merged)

mentioned in merge request kubitus-project/kubitus-installer!2945 (merged)

added releasedpublished label and removed releasedcandidate label

added pipelinetier-3 label