Debate on wiring risk of positive/negative wires along a path
The danger is that the wire insulation chafes, and shorts through to a cell terminal.
The way the cells are arranged means that all voltages from zero to battery voltage are present at the terminals on the top. This means that whether the black wire or the red wire runs across the top, there is an equal set of voltages between the wire and the cell tops, so no theoretical difference between the two arrangements.
There would be no practical difference between the two arrangements either, as the insulation on the wires would usually be substantial enough to resist chafing.
It should be pointed out that the particular arrangement of cells illustrated requires one of the wires to run the length of the battery. There is an alternative arrangement which results in the two terminals being at the same end, so neither wire has to travel the length of the battery. Numbering the cells from 0 at the negative pole, these two arrangements are
illustrated       alternative
 9 6 5 2 1         5 6 7 8 9 
 8 7 4 3 0         4 3 2 1 0