Fenced block containing functions in Doc result in weird aliasing

[SystemFw]

I'm not sure whether I'm doing something unsupported, but the behaviour I'm seeing is very weird. I run from trunk at 172490ab0b. Add this doc to a new project:

hello = {{
 ```
 foo x = x + 1
 ()
 ```
 ```
 bar y = y + 42
 ()
 ```
}}

it renders as:

fwiw, adding foo and bar to the codebase and using @source{ } does not exhibit any issue