Last Teaser-URL seen in side bar render as place holder

[patrickvenetz]

Bug Report

URL input field in side bar contains previous, last Teaser-URL when editing a new Teaser.

This leads to bad judgments in production when checking if URLs are set.

Steps to Reproduce

1. Open (or create) a front (document based on front template)
2. Add a new "Front Tile Row" with 2 teasers
3. Fill in data from an existing article in left teaser
4. Click onto left teaser to see data in side bar
5. Click then onto right teaser

Actual Results

Side bar shows URL linked from left teaser in input field as a place holder in Teaser-URL

Expected Results

Side bar shows blank input field (with label as place holder) in Teaser-URL

Environment

• OS: OSX 10.13.6
• Browser: Chrome 72 (72.0.3626.119)