Mcsat ufnra model fix (#518) #465

Job	Run time
ubuntu-latest\|debug\|--enable-mcsat\|CC=gcc CXX=g++	8m 27s
ubuntu-latest\|debug\|--enable-mcsat\|CC=clang CXX=clang++	8m 40s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=gcc CXX=g++	3m 54s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=clang CXX=clang++	4m 14s
ubuntu-latest\|release\|--enable-mcsat\|CC=gcc CXX=g++	5m 32s
ubuntu-latest\|release\|--enable-mcsat\|CC=clang CXX=clang++	5m 59s
ubuntu-latest\|release\|--enable-thread-safety\|CC=gcc CXX=g++	2m 41s
ubuntu-latest\|release\|--enable-thread-safety\|CC=clang CXX=clang++	2m 36s
ubuntu-latest\|gcov\|--enable-mcsat\|CC=gcc CXX=g++	8m 2s
ubuntu-latest\|debug\|--enable-thread-safety --enable-mcsat\|CC=gcc CXX=g++	8m 15s
	58m 20s

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