Usually, when you move both a rail and the block under a rail together, the rail moves without breaking. But, the rail broke

Steps to Reproduce:
1. Place 2 sticky pistons. One above the other.
2. Place a solid block on the face of the lower sticky piston and either a powered or a regular rail on the face of the top sticky piston.
3. Place 2 target blocks behind the 2 sticky pistons
4. Run Redstone dust into both targets and join the 2 Redstone lines that come from the targets.
5. Place a polished Blackstone button at the end of the Redstone line.
6. Press the button.
7. What should happen is the rail is fine when pushed, but breaks once retracted back.