Comment # 1 on bug 1056700 from Michael Andres

Yes, it might not be that obvious that it's actually a confirmation for a
required vendor change when updating the package. We'll review this.

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NOTE: Tumleweed recently requested to change the default for 'zypper dup' to
'--no-allow-vendor-change' by default. (bug#1031756,libzypp-16.12.1), because
this is the recommended way to update TW.  That's why you now have to confirm
vendor changes.

The old behavior can be achieved by using 'zypper dup --allow-vendor-change' or
permanently by changing 'solver.dupAllowVendorChange' in /etc/zypp/zypp.conf to
'solver.dupAllowVendorChange = true'.