Today i upgraded my testinstall to 1.9.8, and i noticed a few bumps in the upgrade process, mainly the mysql patch:

1) Mysql does not like comments starting with '---', replace them with '-'

Example:
– comment
---- not a comment

select 1
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '---- not a comment select 1' at line 2

2) There is a function called 'zbx_convert_simple_checks'. I'm using a replicated setup with binlogging, so mysql warns me:
#1418 - This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you might want to use the less safe log_bin_trust_function_creators variable)

Both errors will halt the patch at that point, and to continue you need to fix the problem and restart from that position in the patch.