Cannot use <nolink> in link fields in default content

Problem/Motivation

When using <nolink> as the destination URL on a link field that is imported using default content, the import fails with this error:

The URI '<nolink&gtl;' is invalid. You must use a valid URI scheme.

Steps to reproduce

Have default content that includes a link field.

Proposed resolution

Allow link fields with the value '<nolink&gtl;' to be imported using default content.

Remaining tasks

Fix the bug.
Add test coverage.

User interface changes

n/a

Introduced terminology

n/a

API changes

TBC

Data model changes

TBC

Release notes snippet

TBC