The bug

This is a weird bug and kind of hard to explain. The summary is that I placed down two powered rails with a one block gap between them. Then I dug a one block hole in the gap and placed a powered rail there.
The powered rail or normal rail placed there will always connect to only one of the other two powered rails.

What actually happened was that the powered rail or normal rail placed in the hole in between will always connect to only one of the other two powered rails depending on the orientation so for example - I place down the two rails with one block gap between them - the one is facing to the east and one to the west I dig the hole in the middle and place the other rail - the LAST rail placed will ALWAYS connect to the one facing west.

How to reproduce

1. Place two rails or powered rails with a one block gap between them
2. On the gap dig a one block hole
3. Put another rail in the hole - it will always connect to one of the rails mentioned in step 1 NEVER the other no matter what you try to do to connect it to the other.