[3.13] gh-142776: Ensure fp file descriptor is closed on all code paths in import.c (GH-142777) (#142989)

gh-142776: Ensure fp file descriptor is closed on all code paths in import.c (GH-142777)

(cherry picked from commit 6a4f10325d58deb1906b39d68dc8e84f4c2bf5a4)