To regenerate this bug build a trench 1x1 which is long enough for a water block to stop at the end, and place the water block at one end of the trench. Place a dirt block next to the end of the water, and a cobblestone block above the end of the water. Now the water should flow towards (and stop before) the dirt block (see IMG_1072).

However, if you add a water block above the dirt block, it seems like the water is flowing between the dirt and the cobblestone block (see IMG_1073). Note that this is a visual bug, and if you remove the first water block, you'll see that the water doesn't actually flow between the dirt and the cobblestone block (see IMG_1074).