Previously we went into an infinite loop with
```
\newcommand{\noop}[1]{#1}
\noop{\newcommand{\foo}[1]{#1}}
\foo{hi}
```
See #4253.
124 B
124 B
% pandoc -f latex -t native
\newcommand{\noop}[1]{#1}
\noop{\newcommand{\foo}[1]{#1}}
\foo{hi}
^D
[Para [Str "hi"]]