Multicolumns with `layout` in `pdf` output don't work when a column contains a code cell

Quarto 1.6.12.

Here is a reprex:

---
format: pdf
fig-width: 3
fig-height: 1
---

<!-- This works -->
:::: {layout="[ 0.1, 0.9 ]"}
::: {#first-column}
\(a\)
:::
::: {#second-column}
Some text.
:::
::::

<!-- This also works -->
:::: {layout="[ 0.1, 0.9 ]"}
::: {#first-column}
\(b\)
:::
::: {#second-column}
```{r}
#| echo: false
par(mar = c(0, 0, 0, 0))
plot(1:10)
```
:::
::::

<!-- This doesn't exactly work, see how code spans the whole first line -->
:::: {layout="[ 0.1, 0.9 ]"}
::: {#first-column}
\(c\)
:::
::: {#second-column}
```{r}
#| echo: true
par(mar = c(0, 0, 0, 0))
plot(1:10)
```
:::
::::

<!-- This doesn't work, see how code spans the whole first line -->
:::: {layout="[ 0.1, 0.9 ]"}
::: {#first-column}
\(d\)
:::
::: {#second-column}
```{r}
#| eval: false
#| echo: true
par(mar = c(0, 0, 0, 0))
plot(1:10)
```
:::
::::

When the second column contains a code cell that is echoed, it spans the whole width and columns fail.

(Note: When I render this document, (d) is printed on the second page. I think this is the usual LaTeX weird page break issue that is not relevant to this, so I didn't show that in the screenshot above.)

Start by rendering the supplied Markdown reprex with Quarto 1.6.12 and compare the PDF output for echoed and non-echoed R cells inside the two-column layout. Trace the PDF layout handling for code-cell output; done means echoed code remains confined to its assigned column and the layout renders correctly.