Group broken when creating new contact

[lightonflux]

Steps to reproduce

1. Create new group "nextcloud bugs" in a new contact
2. change view to that group
3. create new contact in that view

Expected behaviour

New contact should get the same group that is currently in view. Or none at all.

Actual behaviour

Contact apps splits group name in single letters and adds the new contact to every latter as separate groups:

Server configuration

Operating system: CentOS release 6.8

Web server: apache

Database: sqlite

PHP version: 5.6

Nextcloud version: 11.0.2 (stable)

Contacts version: 1.5.3

Updated from an older Nextcloud or fresh install: updated

Signing status: perfectly signed, no errors

List of activated apps:

Enabled:
  - activity: 2.4.1
  - admin_audit: 1.1.0
  - calendar: 1.5.1
  - comments: 1.1.0
  - contacts: 1.5.3
  - dav: 1.1.1
  - direct_menu: 0.10.0
  - federatedfilesharing: 1.1.1
  - federation: 1.1.1
  - files: 1.6.1
  - files_pdfviewer: 1.0.1
  - files_sharing: 1.1.1
  - files_texteditor: 2.2
  - files_trashbin: 1.1.0
  - files_versions: 1.4.0
  - files_videoplayer: 1.0.0
  - firstrunwizard: 2.0
  - gallery: 16.0.0
  - logreader: 2.0.0
  - lookup_server_connector: 1.0.0
  - nextcloud_announcements: 1.0
  - notifications: 1.0.1
  - password_policy: 1.1.0
  - provisioning_api: 1.1.0
  - serverinfo: 1.1.1
  - sharebymail: 1.0.1
  - survey_client: 0.1.5
  - systemtags: 1.1.3
  - tasks: 0.9.5
  - templateeditor: 0.2
  - theming: 1.1.1
  - twofactor_backupcodes: 1.0.0
  - updatenotification: 1.1.1
  - workflowengine: 1.1.1
Disabled:
  - audioplayer
  - encryption
  - external
  - files_accesscontrol
  - files_automatedtagging
  - files_external
  - files_retention
  - spreed
  - user_external
  - user_ldap
  - user_saml
**Are you using encryption:** no

### Client configuration
**Browser:** Firefox 52

**Operating system:** Debian 9

[irgendwie]

ref. #156