Fix bug blocking the addition of multiple tags

[lnrd96]

User story

1. As a user I want to add several tags to an item.

Acceptance criteria

Several tags can be added by and by. A specific tag can be deleted. These actions are possible on all versions of an item. only the latest version.

Note: The questions whether an old item that changes its tag should receive a new version will be answered on friday https://docs.google.com/document/d/1y1VdDOkj_gLkftg0uH9UBA54rtTJA35-kLW_yp6gGQQ/edit

Notes

The functionality is suspected to be blocked by the following issues:

• empty commit value: when creating new version, because of an added tag
• null commit value needs to be handled
• changing an item by either adding a tag or by uploading a document should be differentiated

Definition of done (DoD)

Feature has been fully implemented No known errors All acceptance criteria were met Test passes Peer code review passed