{{permalink}} with / is rewritten to - in preview_path for preview links

[lsolesen]

Describe the bug

The {{permalink}} has / rewritten to - in preview_path for preview links

To Reproduce

I have the following config.yml -- https://github.com/motionsplan/motionsplan-dk-jekyll/blob/master/admin/config.yml

In my backend I have this permalink:

However, the link generated for View live is the following:

https://www.motionsplan.dk/artikel-unilateral-traening

Expected behavior

Expected to have the link using the permalink as is.

Screenshots

Applicable Versions:

• Netlify CMS version: [e.g. 2.0.4]
• Git provider: [e.g. GitHub, BitBucket]
• OS: [e.g. Windows 7]
• Browser version [e.g. chrome 22, safari 11]

• Node.JS version:

CMS configuration

https://github.com/motionsplan/motionsplan-dk-jekyll/blob/master/admin/config.yml

[erezrokah]

Closing this as duplicate of #4963.
I'll comment #4963