(revision-id: kristofer.pettersson@sun.com-20091019074333-g2ces0lo4c2ejar7),
because it broke the tree and was reverted later.

Fix partition_column.test.

Fixed a use of non-initialised variable, cannot use NULL flags if RANGE == NO_MAX_RANGE or NO_MIN_RANGE, so need to check NULL flags after checking the RANGE isn't NO_MAX_RANGE

Bug#41756 "Strange error messages about locks from InnoDB".
      
In JT_EQ_REF (join_read_key()) access method, 
don't try to unlock rows in the handler, unless certain that 
a) they were locked
b) they are not used.

Unlocking of rows is done by the logic of the nested join loop,
and is unaware of the possible caching that the access method may
have. This could lead to double unlocking, when a row
was unlocked first after reading into the cache, and then 
when taken from cache, as well as to unlocking of rows which
were actually used (but taken from cache).
      
Delegate part of the unlocking logic to the access method,
and in JT_EQ_REF count how many times a record was actually 
used in the join. Unlock it only if it's usage count is 0.

Implemented review comments.

Bug#41756 "Strange error messages about locks from InnoDB".

In JT_EQ_REF (join_read_key()) access method,
don't try to unlock rows in the handler, unless certain that
a) they were locked
b) they are not used.

Unlocking of rows is done by the logic of the nested join loop,
and is unaware of the possible caching that the access method may
have. This could lead to double unlocking, when a row
was unlocked first after reading into the cache, and then
when taken from cache, as well as to unlocking of rows which
were actually used (but taken from cache).

Delegate part of the unlocking logic to the access method,
and in JT_EQ_REF count how many times a record was actually
used in the join. Unlock it only if it's usage count is 0.

Implemented review comments.

- re-enabled main.innodb_bug44369;
- re-enabled main.innodb_bug47777;
- re-enabled innodb.innodb_information_schema.