Flushing and comments

I am running the below code chunk with knitr in RStudio.

<<engine='python'>>=

#comment 1
a = True

a[0] = False

#comment 2


@

The expected output is that it prints an error immediately after a[0] = False but it somehow buffers until after #comment 2 as indicated below:

My temporary fix is to:

<<engine='python', echo=FALSE>>=
def fl():
  import sys
  sys.stdout.flush()
  sys.stderr.flush()
@  

<<engine='python'>>=

#comment 1
a = True

a[0] = False
fl()

#comment 2

@

However, I can't be putting fl() everywhere. How can I make it print before comment 2 without additional lines of code such as fl()?

Reproduce the issue with the knitr Python engine using the code shown, focusing on the output produced after a[0] = False and before #comment 2. Trace how reticulate and knitr capture or flush Python stdout and stderr; done means the error appears before the later comment without adding fl() calls.