Build duration of a plan with manual stage is incorrect

Issue Summary

When a Build contains a manual stage, the build duration is not calculated correctly.

This is reproducible on Data Center:

Steps to Reproduce

1. Add a manual stage to a build that has known build duration.
2. Run the build.
3. Wait 10 minutes before triggering the manual stage.
4. Trigger the manual stage.

in the above scenario the queue time are considered negligible.

Expected Results

The build should have the previous build duration + 10 minutes

Actual Results

The build the build duration is much higher.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available