Pipeline Quota Total Doesn't Match Breakdown

Summary

Group pipelines quota page total does not match total minutes from projects.

Steps to reproduce

1. View the group pipelines quota page.
2. Add minutes from listed next to each project.

Example Project

internal example: https://gitlab.com/groups/dotcom-support-testing/-/pipeline_quota

Total used: 30

Originally reported by customer (internal): https://gitlab.zendesk.com/agent/tickets/114732

What is the current bug behavior?

Adding up minutes from individual projects does not add up to the total. In our case it's a small difference 29 vs. 30, but the customer's is quite different (approx 800 minutes vs. total 10004).

Example project:

Notes from customer report:

• they had no recently deleted projects
• after pipeline minutes were reset, suddenly one project was showing 9370 (was showing 0 before reset)

What is the expected correct behavior?

Numbers add up.

If pipeline quota is reset, everything should reset to 0 or in some other way report on minutes used before/after reset.

Output of checks

GitLab.com, GitLab Enterprise Edition 11.8.0-rc8-ee