`:smtlib2_compliant` setting makes the benchmark `unknown`

[LeventErkok]

For the attached benchmark, z3 currently produces unknown.

However, if I comment out the first line in it, which is merely:

(set-option :smtlib2_compliant true)

then I get a sat answer.

I'm curious why there's this discrepancy; I thought the compliance only impacted what subset of smtlib2 was accepted, not how the solver behaved.

Furthermore, this seems to be a regression since z3 compiled on August 27 of this year produces sat on this benchmark.

compliant_unknown.txt