escaped parentheses cause issues in reticulate REPL

[kevinushey]

For example, if I try to submit the following code to the reticulate REPL:

while False:
  '\('

I see:

>>> while False:
...   '\('
IndentationError: expected an indented block after 'while' statement on line 1 (<string>, line 1)
IndentationError: unexpected indent (<string>, line 1)

Alternatively;

> reticulate::repl_python(input = "while False:\n\t'\\('\n")
Python 3.10.4 (C:/Users/kevin/AppData/Local/Programs/Python/Python310/python.exe)
Reticulate 1.25 REPL -- A Python interpreter in R.
Enter 'exit' or 'quit' to exit the REPL and return to R.
>>>  while False:
...  	'\('
IndentationError: expected an indented block after 'while' statement on line 1 (<string>, line 1)
IndentationError: unexpected indent (<string>, line 1)

[kevinushey]

It looks like there's an underlying error that's getting swallowed here:

debug: ready <- tryCatch(compiler(code), condition = identity)
Browse[2]> code
[1] "while False:\n\t'\\('"
Browse[2]> n
debug: if (is.null(ready)) return()
Browse[2]> ready
<Rcpp::exception in py_call_impl(callable, dots$args, dots$keywords):   File "<input>", line 2
    	'\('
    	^^^^
SyntaxError: invalid escape sequence '\('
>

But yet, I see the following in IDLE:

>>> '\('
    '\\('
>>> while False:
... 	'\('
... 	
    SyntaxError: invalid escape sequence '\('

So this seems like a strange issue in Python itself?

[kevinushey]

Filed python/cpython#96052 upstream; in theory, reticulate could try to work around this but I'm not sure if it's worth the effort.