1) BUG#43309 - Test main.innodb can't be run twice

2) Follow up fix for BUG#43309, adds explanatory comments.

Detailed revision comments:

r4575 | vasil | 2009-03-30 15:55:31 +0300 (Mon, 30 Mar 2009) | 8 lines
branches/5.1:

Fix Bug#43309 Test main.innodb can't be run twice

Make the innodb mysql-test more flexible by inspecting how much a
variable of interest has changed since the start of the test. Do not
assume the variables have zero values at the start of the test.

r4659 | vasil | 2009-04-06 15:34:51 +0300 (Mon, 06 Apr 2009) | 6 lines
branches/5.1:

Followup to r4575 and the fix of Bug#43309 Test main.innodb can't be run twice:

Add an explanatory comment, as suggested by Patrick Crews in the bug report.