The problem was that databases with '_' in the name did not match a
  correct ACL with a literal '_' (i.e. '\_') in the db name, only identical
  strings matched. The fix makes this work, and also ACLs with wildcards in
  the db name work.


mysql-test/r/sp-security.result:
  New test case for BUG#14834
mysql-test/t/sp-security.test:
  New test case for BUG#14834
sql/sql_acl.cc:
  Match wild db:s in ACL in acl_getroot_no_password() (used for "suid" security
  context switching when invoking stored routines)