title: Granting privilege to existing user gives "you are not allowed to create a user with grant" even though the user already exists
body: <p>I am logged in as root user and i just reinstalled the mysql server. login_manager isn't created as is shown when i execute <code>SELECT * FROM mysql.user;</code>. I now execute</p>
  <p><code>CREATE USER 'login_manager'@'localhost' IDENTIFIED BY 'login_manager';</code> and when i check if the user is created, i can find it. Executing</p>
  <pre><code>GRANT INSERT
      ON clients
      TO login_manager;
  </code></pre>
  <p>where client is a table gives me the error i put in the title. Executing <code>FLUSH PRIVILEGES;</code> after creating the user didn't help either. I flushed privileges before creating the user. I looked that up, and normally this error comes when you try to create the user in the grant statement, which i am not doing.</p>
  <p>I know this is long, but here are the Grants that root has:</p>
  <pre><code>'GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, RELOAD, SHUTDOWN, PROCESS, FILE, REFERENCES, INDEX, ALTER, SHOW DATABASES, SUPER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER, CREATE TABLESPACE, CREATE ROLE, DROP ROLE ON *.* TO `root`@`localhost` WITH GRANT OPTION'
  </code></pre>
  <p>and</p>
  <pre><code>'GRANT APPLICATION_PASSWORD_ADMIN,AUDIT_ADMIN,BACKUP_ADMIN,BINLOG_ADMIN,BINLOG_ENCRYPTION_ADMIN,CLONE_ADMIN,CONNECTION_ADMIN,ENCRYPTION_KEY_ADMIN,GROUP_REPLICATION_ADMIN,INNODB_REDO_LOG_ARCHIVE,INNODB_REDO_LOG_ENABLE,PERSIST_RO_VARIABLES_ADMIN,REPLICATION_APPLIER,REPLICATION_SLAVE_ADMIN,RESOURCE_GROUP_ADMIN,RESOURCE_GROUP_USER,ROLE_ADMIN,SERVICE_CONNECTION_ADMIN,SESSION_VARIABLES_ADMIN,SET_USER_ID,SHOW_ROUTINE,SYSTEM_USER,SYSTEM_VARIABLES_ADMIN,TABLE_ENCRYPTION_ADMIN,XA_RECOVER_ADMIN ON *.* TO `root`@`localhost` WITH GRANT OPTION'
  </code></pre>
  <p>and</p>
  <pre><code>'GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION'
  </code></pre>