Water - Does not replenish when filling a bucket

When using a bucket to harvest water from a pool, the removed blocks do not regenerate. I've stopped and restarted the game, I've stopped and restart Minecraft, I've restarted the computer.

This is not a game stopper but, as you can see from the screen shot, it's a tad odd. Interestingly, taking water from a much smaller pool the other side of the path, which barely qualifies as an infinite water source, does not break in this way.

Oh, and this pool is as generated by the world. This part of this village has not yet been touched, except by me falling into this water. World seed is shown in the screen shot. Let me know if you want any additional information.