Why don't strings share data in Python?

[Mike Coleman]

Does anyone know why strings (i.e., those of length >1) don't share their data
in Python?  Since their immutable, it seems like this would be the obvious
thing to do.  So, for example, the space behavior of this code could be linear
rather than quadratic/horrific:

d = {}
for i in xrange(100000000):
    d[mybigstring[i:]] = mybigstring[i:]


Mike