You can fix it if you copy open-url.desktop to /home/[nemo or defaultuser]/.local/share/applications and run next command from Terminal (you must enable ‘Developer mode’ from Settings->Developer Tools to install Terminal):
update-desktop-database $HOME/.local/share/applications/
You can create open-url.desktop yourself with a text editor:
[Desktop Entry]
Type=Application
Name=Browser
Icon=icon-launcher-browser
NoDisplay=true
X-MeeGo-Logical-Id=sailfish-browser-ap-name
X-MeeGo-Translation-Catalog=sailfish-browser
MimeType=text/html;x-scheme-handler/http;x-scheme-handler/https;
X-Maemo-Service=org.sailfishos.browser.ui
X-Maemo-Object-Path=/ui
X-Maemo-Method=org.sailfishos.browser.ui.openUrl
Anyway I think this is a bug and I hope that Jolla fix it