When a wildcard database name is given the mysqlshow, but that wildcard
  matches one database *exactly* (it contains the wildcard character), we
  list the contents of that database instead of just listing the database
  name as matching the wildcard. Probably the most common instance of users
  encountering this behavior would be with "mysqlshow information_schema".


client/mysqlshow.c:
  Add special handling for listing a single database that has a name that
  looked like it contained wildcards. In this case, we just go ahead and list
  the contents of the database, since there is a very high probability that is
  what the user really wanted to do. (For example, 'mysqlshow INFORMATION_SCHEMA'
  will show the I_S tables instead of just the I_S database.)
mysql-test/r/mysqlshow.result:
  Add new results
mysql-test/t/mysqlshow.test:
  Add new regression test