Nested `span`s in markdown gives unexpected output

[Ninjaclasher]

When we have a nested span:

<span> <span> test </span> </span>

The expected text should be:

test

However, we get:

test </span>

For problem descriptions, this happens both with and without full markdown access, so it most likely doesn't have anything to do with bleach.

[Ninjaclasher]

Forgot to mention this doesn't seem to happen with other elements (e.g div).