Bulk operation showing wrong count on progress page

At the end of a Bulk operation, the progress bar count of issues displays more issues being processed than the real selection.
This creates confusion as it appears that JIRA is doing more updates than it was supposed to but the amount of issues processed is correct. Only the displayed number is wrong.

Cause:
An error is happening where, if the issues have sub-tasks, these are included in this count, though they are not updated. The images below illustrate:
Bulk operation:

Message:

Steps to reproduce

1. Create a project (say key ABC) with a sub-task issue type
2. Create an issue (ABC-1)
3. Create a subtask for this issue (ABC-2)
4. Do a JQL search for ABC-1 (key = ABC-1) and bulk edit it
5. Select the issue and some operation for that
   • Has been tested with add comment and edit environment field, but should happen to any operation
6. Go all the way to do the bulk operation

Expected behavior

1. Only ABC-1 is modified
2. The message reads:

   Editing 1 issues

Actual outcome

1. Only ABC-1 is modified (as expected)
2. The message reads:

   Editing 2 issues

It was tested with other number of issues and the count is always the sum of the issues and their sub-tasks.