/gamerule succeeds when the value is not changed

The bug

/gamerule _rule_ <value> succeeds even though <value> equals the current value. This behavior is inconsistent with other commands: /bossbar, /team, and /data.

How to reproduce

1. /gamerule maxCommandChainLength 2

   /gamerule maxCommandChainLength 2

   → ✔ Gamerule maxCommandChainLength is now set to: 2

2. /gamerule maxCommandChainLength 2

   /gamerule maxCommandChainLength 2

   → ❌ Gamerule maxCommandChainLength is now set to: 2