title: ERROR 1267 (HY000): Illegal mix of collations
body: <p>I'm using the Percona mysql client to connect to a database, <code>mysql  Ver 8.0.15-5 for Linux on x86_64 (Source distribution)</code></p>
  
  <pre><code>mysql&gt; SHOW SESSION VARIABLES LIKE 'collation_connection';
  Variable_name   Value
  collation_connection    utf8mb4_general_ci
  mysql&gt; call unit_create_with_dummy_users;
  ERROR 1267 (HY000): Illegal mix of collations (utf8mb4_unicode_520_ci,IMPLICIT) and (utf8mb4_general_ci,IMPLICIT) for operation '='
  mysql&gt;
  </code></pre>
  
  <p>Unlike other error messages like <a href="https://stackoverflow.com/questions/44027987/illegal-mix-of-collations-utf8mb4-unicode-ci-implicit-and-utf8mb4-general-ci">Illegal mix of collations (utf8mb4_unicode_ci,IMPLICIT) and (utf8mb4_general_ci,IMPLICIT) for operation &#39;=&#39;</a> I believe all the tables are of the same collation, but my <strong>collation_connection</strong> isn't? Or perhaps I have misunderstood?</p>