Regression: Cannot duplicate a guide

Summary:

Duplicate guide functionality no longer works in version 1.0

Steps to reproduce:

1. Create a guide
2. Right click the guide > Duplicate
3. Drag the guide aside to see the two copies

What happened?

There is only one guide

What should have happened?

There should be two guides

NOTES:

1. This used to work before version 1.0
2. Using CTRL+D to duplicate the guide doesn't work either

Version Info:

• Inkscape Version: 1.0 (4035a4fb49, 2020-05-01)
• Operating System: Windows
• Operating System version: Windows 10 Home