More bug 460020:  lots of string optimizations inhibited for string
subclasses, all "the usual" ones (slicing etc), plus replace, translate,
ljust, rjust, center and strip.  I don't know how to be sure they've all
been caught.

Question:  Should we complain if someone tries to intern an instance of
a string subclass?  I hate to slow any code on those paths.
2 files changed