Tab completion doesn't change the case of characters typed before pressing tab

When /gamerule dod is typed in chat and TAB is pressed then the third character, "D", is not changed to uppercase to match the actual gamerule, causing the resulting tab-completed command to be /gamerule dodaylightCycle which is invalid.
I would expect the tab autocompletion to change the "D" to uppercase.

This is also the case with other things such as player names.