Making the custom data API const correct in 3a3d9488a1 caused
the issue, because it previously relied on non-threadsafe behavior. As a
workaround, just restore the thread-unsafety, and note the issue in a
new comment.
Making the custom data API const correct in 3a3d9488a1 caused
the issue, because it previously relied on non-threadsafe behavior. As a
workaround, just restore the thread-unsafety, and note the issue in a
new comment.