Manually entered new pattern not saved correctly on Linux environments

[darekhalecki]

Repro:

On Linux environment create a new manual redirect with:

• Old pattern: /test
• New pattern: /test-redirect

The redirect is saved as:

• Old pattern: /test
• New pattern: file:///test-redirect

The new pattern is incorrectly prefixed with file:///.
Possibly because on Linux System.Uri recognizes /test-redirect as an absolute path with a missing scheme.