hash assertion failure after delete/clone.

[coke]

Found this in partcl (causing a very large spec test to fail);

Infinoid++ tracked it down to the following:

.sub main :main
        .local pmc hash1, hash2
        .local string key1, key2
        hash1 = new 'Hash'
        key1 = 'foo'
        key2 = 'bar'
        hash1[key1] = 1
        hash1[key2] = 2
        delete hash1[key1]
        hash2 = clone hash1
        say hash2
.end

I suspect the assertion that the key != NULL is probably a (relatively) recent addition that is causing the failure.

Having this resolved will unstick several hundred spec tests for partcl.

[Infinoid]

Fixed in r35896.