People: Viewer on a private site can't be invited as a member of the site

[rachelmcr]

Expected behavior

If a user is a Viewer on a private site, it should be possible to invite them to become a member (Contributor, Author, Editor, or Administrator) on the same site.

This is possible in Calypso web. If a user is a Viewer on a private site, and you try to invite them as a Viewer again, Calypso shows an error:

But if you select a different role for that Viewer, the invite works:

Actual behavior

If a user is a Viewer on a private site, you are blocked from inviting them to become a member (Contributor, Author, Editor, or Administrator) on the same site.

Steps to reproduce the behavior

1. Select a private site and add a user as a Viewer on that site
2. In the app, go to the site dashboard > People and tap the plus icon to invite a new member
3. Enter the username or email of the Viewer on the site
4. Tap in another field or tap Send

Result: An error appears in red: "There's already a member with the username 'USERNAME'"

Tested on Nexus 9, Android 6.0.1, WPAndroid alpha-16

[stale]

This issue has been marked as stale and will be automatically closed. This happened because:

• It has been inactive for the past year.
• It isn't in a project or a milestone.
• It hasn’t been labeled `[Pri] Blocker`, `[Pri] High`, or `good first issue`.

However, discussion is still welcome! If the issue is still valid, please leave a comment with a brief explanation so the issue can be reopened.