BUG#9998 MySQL client hangs on "USE database"

 Use open_normal_and_derived_tables instead of open_and_lock_tables when reading metadata for a table.
 Add two test cases, one for "USE database" and one for "SHOW COLUMNS FROM table"


mysql-test/r/lock_multi.result:
  Updated test results for test case for bug9998
mysql-test/r/mysql.result:
  Updated results for test case for bug9998
mysql-test/t/lock_multi.test:
  Test that "show columsn from t1" is not locked by another thread having a write lock on t1
mysql-test/t/mysql.test:
  Add test case for BUG9998
    - lock table t1 for write from mysql-test, then execute 'mysql' and call "USE test". This will test exactly what caused the bug.
sql/sql_show.cc:
  Open tables without locking when reading metadata

1 files changed, 12 insertions, 0 deletions

diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test
index cbda47ac864..43cff90332b 100644
--- a/mysql-test/t/lock_multi.test
+++ b/mysql-test/t/lock_multi.test
@@ -94,3 +94,15 @@ connection reader;
 reap;
 connection locker;
 drop table t1;
+
+
+#
+# BUG#9998 - MySQL client hangs on USE "database"
+
+create table t1(a int);
+lock tables t1 write;
+connection reader;
+show columns from t1;
+connection locker;
+unlock tables;
+drop table t1;