Correct ucache bug in ReplaceVariables
Correct ucache bug in ReplaceVariables

If the first variable argument was bound to a nonvariable, the
unification hash cache was preserved when it should have been
invalidated.

bransorem/golog,samuell/golog,samuell/golog,bransorem/golog,vzaramel/golog,mndrix/golog,mndrix/golog,vzaramel/golog