Make the ersatz tests pass

Fixes https://github.com/fpco/stackage/issues/2508

build-constraints.yaml

@@ -3398,9 +3398,6 @@ skipped-tests:
     # criterion
     - store
 
-    # requires custom setup?
-    - ersatz # https://github.com/fpco/stackage/issues/2508
-
 # end of skipped-tests
 
 # Tests which we should build and run, but which are expected to fail. We

debian-bootstrap.sh

@@ -117,6 +117,7 @@ apt-get install -y \
     llvm-3.7 \
     locales \
     m4 \
+    minisat \
     mono-mcs \
     nettle-dev \
     nodejs \