Steps to reproduce for GitHub repository:
1. Go to configuration's Repositories tab
2. Add new repository, select type GitHub
3. Fill mock value in 'Fetch URL' field
4. Delete default value in 'Commit Status Context' field
5. Save repository

Expected result:
Field 'Commit Status Context' is empty.

Actual result:
Value in 'Commit Status Context' field is filled with default value: ${configuration.name}.

Workaround:
Fill field with value ${""}

Same behavior is observed for repository type GitLab (with different default value), and when filling field with spaces. Corresponding field are not present in configuration XML obtained via REST API.