Bulk label editing appends descriptions to epics

Summary

When bulk-editing epics under a project to add a label, the description for one of the epics can be appended to all epics, despite not editing the description for those epics.

This may be related to #228616 (closed)

Steps to reproduce

  1. Have epics under a single project. One of the epics should have a description; the others should not.
  2. Bulk-add labels to all epics (the one with the description, and the ones without)
  3. The epics that did not have a description previously will now have one appended to them from the epic that had a description originally

Example Project

The actual epics affected by this bug are under the business-ops project, and can be seen here (not confidential):

What is the current bug behavior?

A previously-updated description overwrites empty descriptions on epics when bulk-adding of labels occurs.

What is the expected correct behavior?

Bulk-adding labels should only add labels, and should not change any other values in an epic.

Relevant logs and/or screenshots

This was originally reported to SIRT on 2020-07-20 and documented here (note: this issue is confidential). During the initial investigation, I pulled a full day of Rails logs for the affected user to verify what had taken place. If those logs would be helpful, I can provide them (we can either make this issue confidential or I can go through and redact).

Output of checks

This bug happens on GitLab.com

Edited by Marley Riser