Fix AlphaConvertUTest::test_rand_alpha_conversion()
Fix AlphaConvertUTest::test_rand_alpha_conversion()

Geez, this unit test was assuming an overload version of
ScopeLink::alpha_conversion, but was succeeding due the AtomSpace
detecting alpha-equivalent scopes anyway.

rTreutlein/atomspace,rTreutlein/atomspace,rTreutlein/atomspace,AmeBel/atomspace,misgeatgit/atomspace,misgeatgit/atomspace,AmeBel/atomspace,AmeBel/atomspace,misgeatgit/atomspace,AmeBel/atomspace,rTreutlein/atomspace,misgeatgit/atomspace,misgeatgit/atomspace,AmeBel/atomspace,rTreutlein/atomspace