The first time a subinterpreter attempts to import a module without proper subinterpreter support, an `ImportError` is raised (which is correct). However, *subsequent* imports of the same module succeed! Using `readline` as an example, since it's currently single-phase init: ```py >>> from _xxsubinterpreters import create, run_string >>> s = "import readline; print(readline)" >>> interp = create() >>> run_string(interp, s) Traceback (most recent call last): File "<stdin>", line 1, in <module> _xxsubinterpreters.RunFailedError: <class 'ImportError'>: module readline does not support loading in subinterpreters >>> run_string(interp, s) <module 'readline'> ``` <!-- gh-linked-prs --> ### Linked PRs * gh-107184 * gh-107360 <!-- /gh-linked-prs -->