if I run the command:
  zypper in pixz pibzop2
(pibzop2 is misspelled)
on 15.0 I get:
  Loading repository data...
  Reading installed packages...
  'pbzop2' not found in package names. Trying capabilities.
  No provider of 'pbzop2' found.
  Resolving package dependencies...

  The following NEW package is going to be installed:
    pixz

  1 new package to install.

The package not found is skipped and the others can be installed.

The same command on 15.1 gives:

  Loading repository data...
  Reading installed packages...
  'pibzop2' not found in package names. Trying capabilities.
  No provider of 'pibzop2' found.

And no packages is installed at all.